Multiple signaling pathways induced by hexavalent, monospecific and bispecific antibodies for enhanced toxicity to B-cell lymphomas and other diseases

ABSTRACT

Disclosed herein are compositions and methods of use comprising hexavalent DNL complexes. Preferably, the complexes comprise anti-CD20 and/or anti-CD22 antibodies or fragments thereof. More preferably, the anti-CD20 antibody is veltuzumab and the anti-CD22 antibody is epratuzumab. Administration of the subject hexavalent DNL complexes induces apoptosis and cell death of target cells in diseases such as B-cell lymphomas or leukemias, autoimmune disease or immune dysfunction disease. In most preferred embodiments, the DNL complexes increase levels of phosphorylated p38 and PTEN, decrease levels of phosphorylated Lyn, Akt, ERK, IKKα/β and IκBα, increase expression of RKIP and Bax and decrease expression of Mcl-1, Bcl-xL, Bcl-2, and phospho-BAD in target cells. The subject DNL complexes show EC 50  values for inhibiting tumor cell growth in the low nanomolar or even sub-nanomolar concentration range.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 13/668,794 (now U.S. Pat. No. 8,871,216), filed Nov. 5, 2012, which is a divisional of U.S. patent application Ser. No. 13/086,786 (now U.S. Pat. No. 8,349,332), filed Apr. 14, 2011, which claims the benefit under 35 U.S.C. 119(e) of provisional U.S. Patent Application Ser. No. 61/324,111, filed Apr. 14, 2010. This application is a continuation-in-part of U.S. patent application Ser. No. 13/036,820, filed Feb. 28, 2011; Ser. No. 13/021,302, filed Feb. 4, 2011, (which was a divisional of U.S. Pat. No. 7,906,121); which was a divisional of U.S. Pat. No. 7,534,866); Ser. No. 13/012,977, filed Jan. 25, 2011, (which was a divisional of U.S. Pat. No. 7,906,118); Ser. No. 13/010,993, filed Jan. 21, 2011, (which was a divisional of U.S. Pat. No. 7,901,680); Ser. No. 13/004,349, filed Jan. 11, 2011; Ser. No. 12/968,936, filed Dec. 15, 2010, (which was a divisional of U.S. Pat. No. 7,871,622; which was a divisional of U.S. Pat. No. 7,521,056); Ser. No. 12/964,021, filed Dec. 9, 2010; Ser. No. 12/949,536, filed Nov. 18, 2010, (which was a divisional of U.S. Pat. No. 7,858,070; which was a divisional of U.S. Pat. No. 7,527,787); Ser. No. 12/915,515, filed Oct. 29, 2010; Ser. No. 12/871,345, filed Aug. 30, 2010; Ser. No. 12/869,823, filed Aug. 27, 2010; Ser. No. 12/754,740, filed Apr. 6, 2010; Ser. No. 12/752,649, filed Apr. 1, 2010; Ser. No. 12/731,781, filed Mar. 25, 2010; Ser. No. 12/644,146, filed Dec. 22, 2009, (which was a divisional of U.S. Pat. No. 7,666,400); and Ser. No. 12/468,589, filed May 19, 2009, (which was a divisional of U.S. Pat. No. 7,550,143). Those applications claimed the benefit under 35 U.S.C. 119(e) of provisional U.S. Patent Applications 61/414,592, filed Nov. 17, 2010; 61/378,059, filed Aug. 30, 2010; 61/374,449, filed Aug. 17, 2010; 61/323,960, filed Apr. 14, 2010; 61/323,001, filed Apr. 12, 2010; 61/316,996, filed Mar. 24, 2010; 61/302,682, filed Feb. 9, 2010; 61/293,846, filed Jan. 11, 2010; 61/267,877, filed Dec. 9, 2009; 61/266,305, filed Dec. 3, 2009; 61/258,729, filed Nov. 6, 2009; 61/258,369, filed Nov. 5, 2009; 61/238,424, filed Aug. 31, 2009; 61/238,473, filed Aug. 31, 2009; 61/168,668, filed Apr. 13, 2009; 61/168,657, filed Apr. 13, 2009; 61/168,290, filed Apr. 10, 2009; 61/163,666, filed Mar. 26, 2009; 61/119,542, filed Dec. 3, 2008; 61/104,916, filed Oct. 13, 2008; 61/090,487, filed Aug. 20, 2008; 61/043,932, filed Apr. 10, 2008; 60/864,530, filed Nov. 6, 2006; 60/782,332, filed Mar. 14, 2006; 60/751,196, filed Dec. 16, 2005; 60/728,292, filed Oct. 19, 2005; 60/668,603, filed Apr. 6, 2005.

The instant application contains a Sequence Listing which has been submitted in ASCII format via EFS-Web and is hereby incorporated by reference in its entirety. Said ASCII copy, created on May 27, 2011, is named IBC127US.txt and is 54,202 bytes in size.

FIELD OF THE INVENTION

The present invention concerns compositions and methods of use of hexavalent dock-and-lock (DNL) constructs, comprising antibodies and/or antigen-binding antibody fragments. Preferably, the antibodies or fragments thereof bind to CD20 and/or CD22. The compositions and methods are of use for therapy of autoimmune disease, immune dysfunction disease, B-cell lymphomas, B-cell leukemias and other conditions in which disease-associated cells express the target antigens. In preferred embodiments, the compositions and methods exhibit enhanced toxicity to CD20 and/or CD22 expressing target cells, by inducing multiple signaling pathways in the target cell. Such pathways may include, but are not limited to, increased levels of phosphorylated p38, increased levels of PTEN (phosphatase and tensin homolog deleted on chromosome 10), increased apoptosis, decreased levels of phosphorylated Lyn, Akt, ERK, IKKα/β and IκBα, increased expression of RKIP and Bax and decreased expression of Mcl-1, Bcl-xL, Bcl-2, and phospho-BAD. In most preferred embodiments, the compositions and methods are cytotoxic to disease associated cells that express CD20 and/or CD22, with EC₅₀ values in the absence of cross-linking antibodies in the low nanomolar or sub-nanomolar range.

BACKGROUND

To address the clinical concerns of immunogenicity and suboptimal pharmacokinetics, cancer therapy with monoclonal antibodies has evolved from murine to chimeric, humanized, and fully human constructs. Parallel to these improvements have been continuing efforts to develop more effective forms of antibodies, which to date include different antibody isotypes, single-chain antibody fragments with monomeric or multimeric binding moieties, specific mutations in the Fc region to modulate effector function or circulating half-life, and bispecific antibodies of numerous designs that vary in valency, structure, and constituents (Chames et al., Br J Pharmacol 2009, 157:220-233).

Because signaling pathway redundancies can result in lack of response to a single antibody, diverse strategies to use combination therapy with antibodies that bind to different epitopes or different antigens on the same target cell have been proposed. Combinations such as anti-CD20 and anti-CD22 (Stein et al., Clin Cancer Res 2004, 10:2868-2878), anti-CD20 and anti-HLA-DR (Tobin et al., Leuk Lymphoma 2007, 48:944-956), anti-CD20 and anti-TRAIL-R1 (Maddipatla et al., Clin Cancer Res 2007, 13:4556-4564), anti-IGF-1R and anti-EGFR (Goetsche et al., Int J Cancer 2005, 113:316-328), anti-IGF-1R and anti-VEGF (Shang et al., Mol Cancer Ther 2008, 7:2599-2608), or trastuzumab and pertuzumab that target different regions of human EGFR2 (Nahta et al., Cancer Res 2004, 64:2343-2346) have been evaluated preclinically, showing enhanced or synergistic antitumor activity in vitro and in vivo.

The first clinical evidence of an apparent advantage of combining two antibodies against different cancer cell antigens involved the administration of rituximab (chimeric anti-CD20) and epratuzumab (humanized anti-CD22 antibody) in patients with non-Hodgkin lymphoma (NHL). The combination was found to enhance anti-lymphoma efficacy without a commensurate increase in toxicity, based on 3 independent clinical trials (Leonard et al., J Clin Oncol 2005, 23:5044-5051).

Given the number of antibodies approved for cancer therapy, the number of such potential combinations is not large. However, where such combinations show improved efficacy, there is concern over the combined cost of individually expensive antibody therapies, in addition to the inconvenience and time of conducting separate infusions. As an alternative, attempts to develop bispecific antibodies that can simultaneously bind two target antigens have resulted in a multitude of approaches (Chames & Baty, Curr Opin Drug Discov Devel 2009, 12:276-283).

Earlier methods used for the production of bispecific antibodies made use of chemical cross-linking of IgG or Fab′ (Perez et al., Nature 1985, 316:354-356; Glennie et al., J Immunol 1987, 139:2367-2375) or quadromas obtained by fusing two hybridomas together (Staerz & Bevan, Proc Natl Acad Sci USA 1986, 83:1453-1457). Subsequent strategies focused on generating recombinant bispecific antibodies composed of tandem scFvs or diabodies (Kriangkum et al., Biomol Eng 2001, 18:31-40). One format of such Fc-lacking constructs, referred to as BiTe, is currently being tested clinically (Baeuerle & Reinhardt, Cancer Res 2009, 69:4941-4944). Because the presence of an Fc region and its effector functions shows improved in vivo properties for many therapeutic applications, a variety of Fc-containing bispecific antibody designs have also have been suggested (Coloma & Morrison, Nat Biotechnol 1997, 15:159-163; Shen et al., J Biol Chem 2006, 281:10706-10714; Asano et al., J Biol Chem 2007, 282:27659-27665; Wu et al., Nat Biotechnol 2007, 25:1290-1297).

We have developed a novel approach for constructing multivalent antibodies using the dock-and-lock (DNL) method (Rossi et al., Proc Natl Acad Sci USA 2006, 103:6841-6846), which enables site-specific self-assembly of two modular components only with each other. The DNL method results in a covalent structure of defined composition with retained bioactivity (Chang et al., Clin Cancer Res 2007, 13:5586s-5591s). Since the co-administration of anti-CD20 and anti-CD22 antibodies showed improved anti-lymphoma efficacy without increased toxicity in patients (Leonard et al., J Clin Oncol 2005, 23:5044-5051; Leonard & Goldenberg, Oncogene 2007, 26:3704-3713), and enhanced activity in a lymphoma xenograft model (Stein, et al., Clin Cancer Res 2004, 10:2868-2878), the studies reported in the present application utilized the DNL technique to develop hexavalent, monospecific anti-CD20 or bispecific anti-CD20/22 constructs with improved pharmacokinetic properties, increased efficacy and novel mechanisms of action for killing B-cell lymphoma, leukemia or other target cells.

SUMMARY

The present invention concerns improved compositions and methods of use of multivalent, monospecific or bispecific antibodies for therapy of B-cell lymphoma, leukemia and other conditions in which disease-associated cells express target antigens. Preferably, the antibodies are monospecific for CD20 or bispecific for CD20/CD22. In more preferred embodiments, the constructs are hexavalent constructs made by the dock-and-lock (DNL) technique (see, e.g., U.S. Pat. Nos. 7,521,056; 7,527,787; 7,534,866; 7,550,143; 7,666,400; 7,858,070; 7,871,622; 7,901,680; 7,906,118 and 7,906,121, the Examples section of each of which is incorporated herein by reference.) The DNL technique takes advantage of the specific, high-affinity binding interaction between a dimerization and docking domain (DDD) sequence from the regulatory subunit of human cAMP-dependent protein kinase (PKA), such as human PKA RIα, RIβ, RIIα or RIIβ, and an anchor domain (AD) sequence from any of a variety of AKAP proteins. The DDD and AD peptides may be attached to any protein, peptide or other molecule. Because the DDD sequences spontaneously dimerize and bind to the AD sequence, the DNL technique allows the formation of complexes between any selected molecules that may be attached to DDD or AD sequences. Although the standard DNL complex comprises a trimer with two DDD-linked molecules attached to one AD-linked molecule, variations in complex structure allow the formation of dimers, trimers, tetramers, pentamers, hexamers and other multimers. In some embodiments, the DNL complex may comprise two or more antibodies, antibody fragments or fusion proteins which bind to the same antigenic determinant or to two or more different antigens. The DNL complex may also comprise one or more other effectors, such as a cytokine or PEG moiety.

In preferred embodiments, the hexavalent DNL constructs comprise an IgG molecule covalently attached to two copies of an AD moiety, which binds to four Fab fragments, each covalently attached to a DDD moiety. The hexavalent DNL construct therefore comprises six Fab moieties attached to an Fc moiety. By formation of disulfide bonds between the AD and DDD subunits, the entire DNL complex is highly stable under in vivo conditions and each Fab moiety retains the binding specificity and affinity of the parent antibody. In alternative embodiments, the hexavalent DNL construct may comprise 6 anti-CD20 Fabs; 4 anti-CD20 and 2 anti-CD22 Fabs; or 2 anti-CD20 and 4 anti-CD22 Fabs, attached to an Fc moiety. In most preferred embodiments, the hexavalent constructs may comprise the anti-CD22 IgG antibody epratuzumab attached to four Fab subunits of the anti-CD20 antibody veltuzumab (designated 22-20); the veltuzumab IgG attached to four Fab subunits of epratuzumab (designated 20-22); or the veltuzumab IgG attached to four Fab subunits of veltuzumab (designated 20-20) (Rossi et al., Blood 2009, 113:6161-6171; Rossi et al., Cancer Res 2008, 68:8384-8392). Previous studies have shown that 22-20, 20-22, and 20-20 have distinct properties compared with their parental counterparts, including enhanced anti-lymphoma activity in vitro and comparable efficacy in vivo, despite showing shorter circulating half-lives (Rossi et al., Blood 2009, 113:6161-6171; Rossi et al., Cancer Res 2008, 68:8384-8392).

Many examples of anti-CD20 antibodies are known in the art and any such known antibody or fragment thereof may be utilized. In a preferred embodiment, the anti-CD20 antibody is an hA20 antibody (also known as veltuzumab) that comprises the light chain complementarity-determining region (CDR) sequences CDR1 (RASSSVSYIH; SEQ ID NO:1), CDR2 (ATSNLAS; SEQ ID NO:2), and CDR3 (QQWTSNPPT; SEQ ID NO:3) and the heavy chain variable region CDR sequences CDR1 (SYNMH; SEQ ID NO:4), CDR2 (AIYPGNGDTSYNQKFKG; SEQ ID NO:5), and CDR3 (STYYGGDWYFDV; SEQ ID NO:6).

A humanized anti-CD20 antibody suitable for use is disclosed in U.S. Pat. No. 7,435,803, incorporated herein by reference from Col. 36, line 4 through Col. 46, line 52 and FIGS. 1, 2, 4, 5 and 7. However, in alternative embodiments, other known and/or commercially available anti-CD20 antibodies may be utilized, such as rituximab; ofatumumab; ibritumomab; tositumomab; ocrelizumab; GA101; BCX-301; DXL 625; L26, B-Lyl, MEM-97, LT20, 2H7, AT80, B-H20 (ABCAM®, Cambridge, Mass.); HI20a, HI47, 13.6E12 (ABBIOTEC®, San Diego, Calif.); 4f11, Sell, 7d1 (ABD SEROTEC®, Raleigh, N.C.) and any other anti-CD20 antibody known in the art.

The anti-CD20 antibody may be selected such that it competes with or blocks binding to CD20 of an hA20 antibody comprising the light chain complementarity-determining region (CDR) sequences CDR1 (RASSSVSYIH; SEQ ID NO:1), CDR2 (ATSNLAS; SEQ ID NO:2), and CDR3 (QQWTSNPPT; SEQ ID NO:3) and the heavy chain variable region CDR sequences CDR1 (SYNMH; SEQ ID NO:4), CDR2 (AIYPGNGDTSYNQKFKG; SEQ ID NO:5), and CDR3 (STYYGGDWYFDV; SEQ ID NO:6). Alternatively, the anti-CD20 antibody may bind to the same epitope of CD20 as a hA20 antibody.

Many examples of anti-CD22 antibodies are also known in the art and any such known antibody or fragment thereof may be utilized. In a preferred embodiment, the anti-CD22 antibody is an hLL2 antibody (also known as epratuzumab) that comprises the light chain CDR sequences CDR1 (KSSQSVLYSANHKYLA, SEQ ID NO:7), CDR2 (WASTRES, SEQ ID NO:8), and CDR3 (HQYLSSWTF, SEQ ID NO:9) and the heavy chain CDR sequences CDR1 (SYWLH, SEQ ID NO:10), CDR2 (YINPRNDYTEYNQNFKD, SEQ ID NO:11), and CDR3 (RDITTFY, SEQ ID NO:12). A humanized LL2 anti-CD22 antibody suitable for use is disclosed in U.S. Pat. No. 6,187,287, incorporated herein by reference from Col. 11, line 40 through Col. 20, line 38 and FIGS. 1, 4 and 5. However, in alternative embodiments, other known and/or commercially available anti-CD22 antibodies may be utilized, such as 1F5; HIB22 (ABBIOTEC®, San Diego, Calif.); FPC1, LT22, MEM-1, RFB4 (ABCAM®, Cambridge, Mass.); bu59, fpc1, mc64-12 (ABD SEROTEC®, Raleigh, N.C.); IS7 (ABNOVA®, Taipei City, Taiwan) and any other anti-CD22 antibody known in the art.

The anti-CD22 antibody may be selected such that it competes with or blocks binding to CD22 of an LL2 antibody comprising the light chain CDR sequences CDR1 (KSSQSVLYSANHKYLA, SEQ ID NO:7), CDR2 (WASTRES, SEQ ID NO:8), and CDR3 (HQYLSSWTF, SEQ ID NO:9) and the heavy chain CDR sequences CDR1 (SYWLH, SEQ ID NO:10), CDR2 (YINPRNDYTEYNQNFKD, SEQ ID NO:11), and CDR3 (RDITTFY, SEQ ID NO:12). Alternatively, the anti-CD22 antibody may bind to the same epitope of CD22 as an LL2 antibody.

The anti-CD20 and/or anti-CD22 antibodies or fragments thereof may be used as naked antibodies, alone or in combination with one or more therapeutic agents. Alternatively, the antibodies or fragments may be utilized as immunoconjugates, attached to one or more therapeutic agents. (For methods of making immunoconjugates, see, e.g., U.S. Pat. Nos. 4,699,784; 4,824,659; 5,525,338; 5,677,427; 5,697,902; 5,716,595; 6,071,490; 6,187,284; 6,306,393; 6,548,275; 6,653,104; 6,962,702; 7,033,572; 7,147,856; and 7,259,240, the Examples section of each incorporated herein by reference.) Therapeutic agents may be selected from the group consisting of a radionuclide, a cytotoxin, a chemotherapeutic agent, a drug, a pro-drug, a toxin, an enzyme, an immunomodulator, an anti-angiogenic agent, a pro-apoptotic agent, a cytokine, a hormone, an oligonucleotide molecule (e.g., an antisense molecule or a gene) or a second antibody or fragment thereof.

The therapeutic agent may be selected from the group consisting of aplidin, azaribine, anastrozole, azacytidine, bleomycin, bortezomib, bryostatin-1, busulfan, calicheamycin, camptothecin, 10-hydroxycamptothecin, carmustine, celebrex, chlorambucil, cisplatin, irinotecan (CPT-11), SN-38, carboplatin, cladribine, cyclophosphamide, cytarabine, dacarbazine, docetaxel, dactinomycin, daunomycin glucuronide, daunorubicin, dexamethasone, diethylstilbestrol, doxorubicin, doxorubicin glucuronide, epirubicin glucuronide, ethinyl estradiol, estramustine, etoposide, etoposide glucuronide, etoposide phosphate, floxuridine (FUdR), 3′,5′-O-dioleoyl-FudR (FUdR-dO), fludarabine, flutamide, fluorouracil, fluoxymesterone, gemcitabine, hydroxyprogesterone caproate, hydroxyurea, idarubicin, ifosfamide, L-asparaginase, leucovorin, lomustine, mechlorethamine, medroprogesterone acetate, megestrol acetate, melphalan, mercaptopurine, 6-mercaptopurine, methotrexate, mitoxantrone, mithramycin, mitomycin, mitotane, phenyl butyrate, prednisone, procarbazine, paclitaxel, pentostatin, PSI-341, semustine streptozocin, tamoxifen, taxanes, taxol, testosterone propionate, thalidomide, thioguanine, thiotepa, teniposide, topotecan, uracil mustard, velcade, vinblastine, vinorelbine, vincristine, ricin, abrin, ribonuclease, onconase, rapLR1, DNase I, Staphylococcal enterotoxin-A, pokeweed antiviral protein, gelonin, diphtheria toxin, Pseudomonas exotoxin, and Pseudomonas endotoxin.

The therapeutic agent may comprise a radionuclide selected from the group consisting of ^(103m)Rh, ¹⁰³Ru, ¹⁰⁵Rh, ¹⁰⁵Ru, ¹⁰⁷Hg, ¹⁰⁹Pd, ¹⁰⁹Pt, ¹¹¹Ag, ¹¹¹In, ^(113m)In, ¹¹⁹Sb, ¹¹C, ^(121m)Te, ^(122m)Te, ¹²⁵I, ^(125m)Te, ¹²⁶I, ¹³¹I, ¹³³I, ¹³N, ¹⁴²Pr, ¹⁴³Pr, ¹⁴⁹Pm, ¹⁵²Dy, ¹⁵³Sm, ¹⁵O, ¹⁶¹Ho, ¹⁶¹Tb, ¹⁶⁵Tm, ¹⁶⁶Dy, ¹⁶⁶Ho, ¹⁶⁷Tm, ¹⁶⁸Tm, ¹⁶⁹Er, ¹⁶⁹Yb, ¹⁷⁷Lu, ¹⁸⁶Re, ¹⁸⁸Re, ^(189m)Os, ¹⁸⁹Re, ¹⁹²Ir, ¹⁹⁴Ir, ¹⁹⁷Pt, ¹⁹⁸Au, ¹⁹⁹Au, ²⁰¹Tl, ²⁰³Hg, ²¹¹At, ²¹¹Bi, ²¹¹Pb, ²¹²Bi, ²¹²Pb, ²¹³Bi, ²¹⁵Po, ²¹⁷At, ²¹⁹Rn, ²²¹Fr, ²²³Ra, ²²⁴Ac, ²²⁵Ac, ²²⁵Fm, ³²P, ³³P, ⁴⁷Sc, ⁵¹Cr, ⁵⁷Co, ⁵⁸Co, ⁵⁹Fe, ⁶²Cu, ⁶⁷Cu, ⁶⁷Ga, ⁷⁵Br, ⁷⁵Se, ⁷⁶Br, ⁷⁷As, ⁷⁷Br, ^(80m)Br, ⁸⁹Sr, ⁹⁰Y, ⁹⁵Ru, ⁹⁷Ru, ⁹⁹Mo and ^(99m)Tc.

The therapeutic agent may be an enzyme selected from the group consisting of malate dehydrogenase, staphylococcal nuclease, delta-V-steroid isomerase, yeast alcohol dehydrogenase, alpha-glycerophosphate dehydrogenase, triose phosphate isomerase, horseradish peroxidase, alkaline phosphatase, asparaginase, glucose oxidase, beta-galactosidase, ribonuclease, urease, catalase, glucose-6-phosphate dehydrogenase, glucoamylase and acetylcholinesterase.

An immunomodulator of use may be selected from the group consisting of a cytokine, a stem cell growth factor, a lymphotoxin, a hematopoietic factor, a colony stimulating factor (CSF), an interferon (IFN), erythropoietin, thrombopoietin and combinations thereof. Exemplary immunomodulators may include IL-1, IL-2, IL-3, IL-6, IL-10, IL-12, IL-18, IL-21, interferon-α, interferon-β, interferon-γ, G-CSF, GM-CSF, and mixtures thereof.

Exemplary anti-angiogenic agents may include angiostatin, endostatin, basculostatin, canstatin, maspin, anti-VEGF binding molecules, anti-placental growth factor binding molecules, or anti-vascular growth factor binding molecules.

In certain embodiments, the antibody or fragment may comprise one or more chelating moieties, such as NOTA, DOTA, DTPA, TETA, Tscg-Cys, or Tsca-Cys. In certain embodiments, the chelating moiety may form a complex with a therapeutic or diagnostic cation, such as Group II, Group III, Group IV, Group V, transition, lanthanide or actinide metal cations, Tc, Re, Bi, Cu, As, Ag, Au, At, or Pb.

In some embodiments, the antibody or fragment thereof may be a human, chimeric, or humanized antibody or fragment thereof. A humanized antibody or fragment thereof may comprise the complementarity-determining regions (CDRs) of a murine antibody and the constant and framework (FR) region sequences of a human antibody, which may be substituted with at least one amino acid from corresponding FRs of a murine antibody. A chimeric antibody or fragment thereof may include the light and heavy chain variable regions of a murine antibody, attached to human antibody constant regions. The antibody or fragment thereof may include human constant regions of IgG1, IgG2a, IgG3, or IgG4. Exemplary known antibodies of use include, but are not limited to, hR1 (anti-IGF-1R), hPAM4 (anti-mucin), hA20 (anti-CD20), hA19 (anti-CD19), hIMMU31 (anti-AFP), hLL1 (anti-CD74), hLL2 (anti-CD22), hMu-9 (anti-CSAp), hL243 (anti-HLA-DR), hMN-14 (anti-CEACAM5), hMN-15 (anti-CEACAM6), 29H2 (anti-CEACAM1, ABCAM®), hRS7 (anti-EGP-1) and hMN-3 (anti-CEACAM6).

Although in preferred embodiments that antibodies or fragments thereof incorporated into the hexavalent constructs bind to CD20 and/or CD22, in alternative embodiments antibodies or fragments may bind to one or more target antigens selected from the group consisting of carbonic anhydrase IX, alpha-fetoprotein, α-actinin-4, A3, antigen specific for A33 antibody, ART-4, B7, Ba 733, BAGE, BrE3-antigen, CA125, CAMEL, CAP-1, CASP-8/m, CCCL19, CCCL21, CD1, CD1a, CD2, CD3, CD4, CD5, CD8, CD11A, CD14, CD15, CD16, CD18, CD19, CD20, CD21, CD22, CD23, CD25, CD29, CD30, CD32b, CD33, CD37, CD38, CD40, CD40L, CD45, CD46, CD52, CD54, CD55, CD59, CD64, CD66a-e, CD67, CD70, CD74, CD79a, CD80, CD83, CD95, CD126, CD133, CD138, CD147, CD154, CDC27, CDK-4/m, CDKN2A, CXCR4, colon-specific antigen-p (CSAp), CEA (CEACAM5), CEACAM1, CEACAM6, c-met, DAM, EGFR, EGFRvIII, EGP-1, EGP-2, ELF2-M, Ep-CAM, Flt-1, Flt-3, folate receptor, G250 antigen, GAGE, gp100, GROB, HLA-DR, HM1.24, human chorionic gonadotropin (HCG) and its subunits, HER2/neu, HMGB-1, hypoxia inducible factor (HIF-1), HSP70-2M, HST-2, Ia, IGF-1R, IFN-γ, IFN-α, IFN-β, IL-2, IL-4R, IL-6R, IL-13R, IL-15R, IL-17R, IL-18R, IL-6, IL-8, IL-12, IL-15, IL-17, IL-18, IL-25, insulin-like growth factor-1 (IGF-1), KC4-antigen, KS-1-antigen, KS1-4, Le-Y, LDR/FUT, macrophage migration inhibitory factor (MIF), MAGE, MAGE-3, MART-1, MART-2, NY-ESO-1, TRAG-3, mCRP, MCP-1, MIP-1A, MIP-1B, MIF, MUC1, MUC2, MUC3, MUC4, MUC5, MUM-1/2, MUM-3, NCA66, NCA95, NCA90, antigen specific for PAM-4 antibody, placental growth factor, p53, PLAGL2, prostatic acid phosphatase, PSA, PRAME, PSMA, PlGF, IGF, IGF-1R, IL-6, IL-25, RS5, RANTES, T101, SAGE, 5100, survivin, survivin-2B, TAC, TAG-72, tenascin, TRAIL receptors, TNF-α, Tn antigen, Thomson-Friedenreich antigens, tumor necrosis antigens, VEGFR, ED-B fibronectin, WT-1, 17-1A-antigen, complement factors C3, C3a, C3b, C5a, C5, an angiogenesis marker, bcl-2, bcl-6, Kras, cMET, an oncogene marker and an oncogene product (see, e.g., Sensi et al., Clin Cancer Res 2006, 12:5023-32; Parmiani et al., J Immunol 2007, 178:1975-79; Novellino et al. Cancer Immunol Immunother 2005, 54:187-207). Reports on tumor associated antigens include Mizukami et al., (2005, Nature Med. 11:992-97); Hatfield et al., (2005, Curr. Cancer Drug Targets 5:229-48); Vallbohmer et al. (2005, J. Clin. Oncol. 23:3536-44); and Ren et al. (2005, Ann. Surg. 242:55-63).

Also disclosed is a method for treating and/or diagnosing a disease or disorder that includes administering to a patient a therapeutic and/or diagnostic composition that includes any of the aforementioned antibodies or fragments thereof. Typically, the composition is administered to the patient intravenously, intramuscularly or subcutaneously at a dose of 20-5000 mg. In preferred embodiments, the disease or disorder is a B-cell lymphoma or leukemia, an immune dysregulation disease, an autoimmune disease, organ-graft rejection or graft-versus-host disease. More preferably, the disease is a B-cell lymphoma or leukemia. Exemplary malignancies that may be treated using the claimed methods and compositions include, but are not limited to, indolent forms of B-cell lymphomas, aggressive forms of B-cell lymphomas, acute lymphocytic leukemia, chronic lymphocytic leukemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma, mantle cell lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, marginal zone lymphoma, Burkitt's lymphoma and multiple myeloma

Exemplary autoimmune diseases include acute idiopathic thrombocytopenic purpura, chronic idiopathic thrombocytopenic purpura, dermatomyositis, Sydenham's chorea, myasthenia gravis, systemic lupus erythematosus, lupus nephritis, rheumatic fever, polyglandular syndromes, bullous pemphigoid, diabetes mellitus, Henoch-Schonlein purpura, post-streptococcal nephritis, erythema nodosum, Takayasu's arteritis, Addison's disease, rheumatoid arthritis, multiple sclerosis, sarcoidosis, ulcerative colitis, erythema multiforme, IgA nephropathy, polyarteritis nodosa, ankylosing spondylitis, Goodpasture's syndrome, thromboangitis obliterans, Sjogren's syndrome, primary biliary cirrhosis, Hashimoto's thyroiditis, thyrotoxicosis, scleroderma, chronic active hepatitis, polymyositis/dermatomyositis, polychondritis, pemphigus vulgaris, Wegener's granulomatosis, membranous nephropathy, amyotrophic lateral sclerosis, tabes dorsalis, giant cell arteritis/polymyalgia, pernicious anemia, rapidly progressive glomerulonephritis, psoriasis, or fibrosing alveolitis.

In particularly preferred embodiments, administration DNL complexes comprising anti-CD20 and/or anti-CD22 antibodies or fragments thereof can deplete disease-associated cells by mechanisms including, but not limited to, increasing levels of phosphorylated p38, increasing levels of PTEN, increasing apoptosis, decreasing levels of phosphorylated Lyn, Akt, ERK, IKKα/β and IκBα, increasing expression of RKIP and Bax and decreasing expression of Mcl-1, Bcl-xL, Bcl-2, and phospho-BAD.

BRIEF DESCRIPTION OF THE DRAWINGS

The following Figures are provided to illustrate exemplary, but non-limiting, preferred embodiments of the invention. The following terms were used interchangeably in designating hexavalent DNL constructs.

-   -   20-20: Also referred to as Hex-hA20, comprising an anti-CD20         hA20 IgG attached to four anti-CD20 hA20 Fab moieties.     -   20-22: Also referred to as DNL2, comprising an anti-CD20 hA20         IgG attached to four anti-CD22 hLL2 Fab moieties.     -   22-20: Also referred to as DNL1, comprising an anti-CD22 hLL2         IgG attached to four anti-CD20 hA20 Fab moieties.

FIG. 1. Competitive ELISA experiments to compare the relative hA20/hLL2 binding avidities of DNL1, DNL2, Hex-hA20 and Hex-hLL2 with the parental IgGs. Microtiter plates were coated with hA20 or hLL2 IgG at 5 μg/ml. Dilution series of the HIDS were mixed with anti-Ids specific to hA20 or hLL2 IgG, which was maintained at a constant concentration (2 nM). The level of binding of the anti-Ids to the coated wells was detected using peroxidase-conjugated-Goat anti-Rat IgG and OPD substrate solution. The results are plotted as % inhibition (of anti-Id binding to coated wells) vs. concentration of HIDS. EC₅₀ (the effective concentration resulting in 50% inhibition) values were derived using Prism software. The HIDS were used to compete for binding to (A) WI2 (hA20 Rat anti-Id) in hA20-coated wells or (B) WN (hLL2 Rat anti-Id) in hLL2-coated wells.

FIG. 2. Dose-response experiment for treatment of Daudi cells with various HIDS. Cells were plated in 96-well plates at 5,000 cells/well in RPMI 1640 media. Five-fold serial dilutions were performed in triplicate from concentrations of 2×10⁻⁸ down to 6.4×10⁻¹²M. The plates were incubated for four days, after which MTS reagent was added and the incubation was continued for an additional four hours before reading the plates at 490 nm. The results are given as percent of the OD₄₉₀ for untreated wells vs. the log of the molar concentration of HIDS. EC₄₀ (the effective concentration resulting in 40% growth inhibition) values were measured for each dose-response curve.

FIG. 3. In vivo therapy of mice bearing human Burkitt Lymphoma (Daudi) treated with DNL2 or Hex-hA20. Mice (4/group) were inoculated i.v. with 1.5×10⁷ Daudi cells (day 0). On days 1, 4 and 7, mice were administered either 4 μg or 20 μg of DNL2 or Hex-hA20 intraperitoneally (i.p.). Mice were sacrificed if they developed either hind-limb paralysis or lost >20% body weight. The results are plotted as % survival vs. time (days). Median survival and long term survivors are shown.

FIG. 4. Relative dose-response curves generated using an MTS proliferation assay for Daudi cells, Raji cells and Ramos cells treated with a bispecific HID (DNL2—four hLL2 Fab fragments tethered to an hA20 IgG) and a monospecific HID (Hex-hA20), compared with an hA20 IgG control. In Daudi cells (top panel), DNL2 showed >100-fold and Hex-hA20 showed >10,000 fold more potent antiproliferative activity than hA20 IgG. In Raji cells (middle panel), Hex-hA20 displayed potent anti-proliferative activity, while DNL2 showed only minimal activity, compared to hA20 IgG. In Ramos cells (bottom panel), both DNLs and Hex-hA20 displayed potent anti-proliferative activity compared to hA20 IgG.

FIG. 5. In vitro cytotoxicity as determined by the MTS assay and apoptosis by the annexin V staining Results shown are for Daudi (A), Raji (B), RL and DoHH2 (C), and the annexin V binding assay for Daudi (D). The concentrations of each primary antibody and GAH were 10 nM and 10 μg/mL, respectively.

FIG. 6. Western blot analysis of proteins induced in Daudi by the parental antibodies and HexAbs. (A) Effect on phospho-Lyn, phospho-Syk, phosph-PLCγ2 and β-actin control of epratuzumab, rituximab, veltuzumab, 20-20, 22-20, 20-22 and control anti-IgM. (B) Time course of effects of phospho-Lyn and Lyn of 20-20, 22-20 and 20-22. (C) Effect on phospho-AKT, AKT and β-actin control of epratuzumab, rituximab, veltuzumab, 20-20, 22-20 and 20-22. (D) Effect on RKIP vs. β-actin control of epratuzumab, rituximab, veltuzumab, 20-20, 22-20 and 20-22. (E) Effect on phospho-Lyn and phospho-AKT vs. β-actin control of epratuzumab, rituximab, veltuzumab, 20-20, 22-20 and 20-22. Parent antibodies used were each at 133 nM (A, C, D) or 10 nM (E). The HexAbs used were each at 10 nM (A-E); or anti-IgM, at 10 μg/mL (A, C). The changes in phospho-Lyn observed with 20-20, 22-20, and 20-22 within the first 24 hours are shown in (B).

FIG. 7. Modulation of ERK1/2 and p38 MAPK pathways. (A) Daudi cells were treated with 133 nM each of rituximab, epratuzumab, and veltuzumab and 10 nM each of 20-20, 22-20, and 20-22 separately for 24 hours. Cells were immunoblotted and probed with phospho-specific antibodies as well as with antibodies to ERK1/2, p38, and β-actin. Bar diagrams show the relative intensity of phospho-ERK or phospho-p38 induced by each agent, as determined by densitometry analysis of the results from 2 or more independent experiments. (B) Phospho-ERK1/2 induced by 20-20, 22-20, and 20-22 or rituximab at 10 nM measured at various time points within the first 24 hours. (C) Up-regulation of phospho-ERK1/2 by crosslinking rituximab and veltuzumab with GAH (10 μg/mL).

FIG. 8. Effects observed in Daudi cells. (A) Selective proteins pertaining to the NF-κB pathway, (B) selective proteins pertaining to the Bcl-2 family, and (C) mitochondrial membrane depolarization.

FIG. 9. PTEN-PI3K pathway. (A) Time course of PTEN after treating Daudi cells with 20-20, 22-20, and 20-22 at 10 nM and rituximab at 133 nM. The sample corresponding to 20-22 at 24 hours was lost during loading and thus not analyzed. (B) Daudi cells transfected with PTEN siRNA showed reduced expression of PTEN, compared with the untreated cells or cells transfected with control siRNA. (C) PTEN siRNA reduced the apoptosis of Daudi by 20-20, 22-20, and 20-22 at 10 nM (P values with respect to *20-20, #22-20, and **20-22; P<0.05). (D) The PI3K inhibitor, LY294002 (5 μM), enhanced the apoptosis induced by 20-20, 22-20, and 20-22 at 10 nM, but not rituximab at 133 nM.

FIG. 10A. Deregulation of cell cycle. Histograms obtained from Daudi cells treated with 100 nM of each agent, showing G₁ arrest induced by 20-20, 22-20, and 20-22.

FIG. 10B. Deregulation of cell cycle. Comparison of cells in the G₁ phase after treatment with each agent at 10 or 100 nM.

FIG. 10AC. Deregulation of cell cycle. Up-regulation of the Cip/Kip family of proteins on treatment with 20-20, 20-22, and 22-20.

FIG. 10D. Deregulation of cell cycle. Down-regulation of cyclin D1 and p-Rb.

DETAILED DESCRIPTION

Definitions

As used herein, the terms “a”, “an” and “the” may refer to either the singular or plural, unless the context otherwise makes clear that only the singular is meant.

An “antibody” refers to a full-length (i.e., naturally occurring or formed by normal immunoglobulin gene fragment recombinatorial processes) immunoglobulin molecule (e.g., an IgG antibody) or an immunologically active (i.e., antigen-binding) portion of an immunoglobulin molecule, like an antibody fragment.

An “antibody fragment” is a portion of an antibody such as F(ab′)₂, F(ab)₂, Fab′, Fab, Fv, scFv, single domain antibodies (DABs or VHHs) and the like, including half-molecules of IgG4 (van der Neut Kolfschoten et al. (Science 2007; 317 (14 September):1554-1557). Regardless of structure, an antibody fragment binds with the same antigen that is recognized by the intact antibody. For example, an anti-CD20 antibody fragment binds with an epitope of CD20. The term “antibody fragment” also includes isolated fragments consisting of the variable regions, such as the “Fv” fragments consisting of the variable regions of the heavy and light chains and recombinant single chain polypeptide molecules in which light and heavy chain variable regions are connected by a peptide linker (“scFv proteins”).

A “chimeric antibody” is a recombinant protein that contains the variable domains including the complementarity determining regions (CDRs) of an antibody derived from one species, preferably a rodent antibody, while the constant domains of the antibody molecule are derived from those of a human antibody. For veterinary applications, the constant domains of the chimeric antibody may be derived from that of other species, such as a cat or dog.

A “humanized antibody” is a recombinant protein in which the CDRs from an antibody from one species; e.g., a rodent antibody, are transferred from the heavy and light variable chains of the rodent antibody into human heavy and light variable domains. Additional FR amino acid substitutions from the parent, e.g. murine, antibody may be made. The constant domains of the antibody molecule are derived from those of a human antibody.

A “human antibody” is, for example, an antibody obtained from transgenic mice that have been genetically engineered to produce human antibodies in response to antigenic challenge. In this technique, elements of the human heavy and light chain locus are introduced into strains of mice derived from embryonic stem cell lines that contain targeted disruptions of the endogenous heavy chain and light chain loci. The transgenic mice can synthesize human antibodies specific for human antigens, and the mice can be used to produce human antibody-secreting hybridomas. Methods for obtaining human antibodies from transgenic mice are described by Green et al., Nature Genet. 7:13 (1994), Lonberg et al., Nature 368:856 (1994), and Taylor et al., Int. Immun. 6:579 (1994). A fully human antibody also can be constructed by genetic or chromosomal transfection methods, as well as phage display technology, all of which are known in the art. (See, e.g., McCafferty et al., Nature 348:552-553 (1990) for the production of human antibodies and fragments thereof in vitro, from immunoglobulin variable domain gene repertoires from unimmunized donors). In this technique, antibody variable domain genes are cloned in-frame into either a major or minor coat protein gene of a filamentous bacteriophage, and displayed as functional antibody fragments on the surface of the phage particle. Because the filamentous particle contains a single-stranded DNA copy of the phage genome, selections based on the functional properties of the antibody also result in selection of the gene encoding the antibody exhibiting those properties. In this way, the phage mimics some of the properties of the B cell. Phage display can be performed in a variety of formats, for their review, see, e.g. Johnson and Chiswell, Current Opinion in Structural Biology 3:5564-571 (1993). Human antibodies may also be generated by in vitro activated B cells. (See, U.S. Pat. Nos. 5,567,610 and 5,229,275).

A “therapeutic agent” is an atom, molecule, or compound that is useful in the treatment of a disease. Examples of therapeutic agents include but are not limited to antibodies, antibody fragments, drugs, toxins, enzymes, nucleases, hormones, immunomodulators, antisense oligonucleotides, chelators, boron compounds, photoactive agents, dyes and radioisotopes.

A “diagnostic agent” is an atom, molecule, or compound that is useful in diagnosing a disease. Useful diagnostic agents include, but are not limited to, radioisotopes, dyes, contrast agents, fluorescent compounds or molecules and enhancing agents (e.g., paramagnetic ions). Preferably, the diagnostic agents are selected from the group consisting of radioisotopes, enhancing agents, and fluorescent compounds.

An “immunoconjugate” is a conjugate of an antibody, antibody fragment, antibody fusion protein, bispecific antibody or multispecific antibody with an atom, molecule, or a higher-ordered structure (e.g., with a carrier, a therapeutic agent, or a diagnostic agent). A “naked antibody” is an antibody that is not conjugated to any other agent.

As used herein, the term “antibody fusion protein” is a recombinantly produced antigen-binding molecule in which an antibody or antibody fragment is covalently linked to another protein or peptide, such as the same or different antibody or antibody fragment or a DDD or AD peptide. The fusion protein may comprise a single antibody component, a multivalent or multispecific combination of different antibody components or multiple copies of the same antibody component. The fusion protein may additionally comprise an antibody or an antibody fragment and a therapeutic agent. Examples of therapeutic agents suitable for such fusion proteins include immunomodulators and toxins. One preferred toxin comprises a ribonuclease (RNase), preferably a recombinant RNase.

A “multispecific antibody” is an antibody that can bind simultaneously to at least two targets that are of different structure, e.g., two different antigens, two different epitopes on the same antigen, or a hapten and/or an antigen or epitope. A “multivalent antibody” is an antibody that can bind simultaneously to at least two targets that are of the same or different structure. Valency indicates how many binding arms or sites the antibody has to a single antigen or epitope; i.e., monovalent, bivalent, trivalent or multivalent. The multivalency of the antibody means that it can take advantage of multiple interactions in binding to an antigen, thus increasing the avidity of binding to the antigen. Specificity indicates how many antigens or epitopes an antibody is able to bind; i.e., monospecific, bispecific, trispecific, multispecific. Using these definitions, a natural antibody, e.g., an IgG, is bivalent because it has two binding arms but is monospecific because it binds to one epitope. Multispecific, multivalent antibodies are constructs that have more than one binding site of different specificity. For example, a diabody, where one binding site reacts with one antigen and the other with another antigen.

A “bispecific antibody” is an antibody that can bind simultaneously to two targets which are of different structure.

Dock-and-Lock (DNL)

In preferred embodiments, multivalent monospecific or bispecific antibodies may be produced using the dock-and-lock (DNL) technology (see, e.g., U.S. Pat. Nos. 7,521,056; 7,550,143; 7,534,866; 7,527,787 and 7,666,400; the Examples section of each of which is incorporated herein by reference). The DNL method exploits specific protein/protein interactions that occur between the regulatory (R) subunits of cAMP-dependent protein kinase (PKA) and the anchoring domain (AD) of A-kinase anchoring proteins (AKAPs) (Baillie et al., FEBS Letters. 2005; 579: 3264. Wong and Scott, Nat. Rev. Mol. Cell. Biol. 2004; 5: 959). PKA, which plays a central role in one of the best studied signal transduction pathways triggered by the binding of the second messenger cAMP to the R subunits, was first isolated from rabbit skeletal muscle in 1968 (Walsh et al., J. Biol. Chem. 1968; 243:3763). The structure of the holoenzyme consists of two catalytic subunits held in an inactive form by the R subunits (Taylor, J. Biol. Chem. 1989; 264:8443). Isozymes of PKA are found with two types of R subunits (R1 and R11), and each type has α and β isoforms (Scott, Pharmacol. Ther. 1991; 50:123). Thus, there are four types of PKA regulatory subunits—RIα, RIIβ, RIIα and RIIβ. The R subunits have been isolated only as stable dimers and the dimerization domain has been shown to consist of the first 44 amino-terminal residues (Newlon et al., Nat. Struct. Biol. 1999; 6:222). Binding of cAMP to the R subunits leads to the release of active catalytic subunits for a broad spectrum of serine/threonine kinase activities, which are oriented toward selected substrates through the compartmentalization of PKA via its docking with AKAPs (Scott et al., J. Biol. Chem. 1990; 265; 21561).

Since the first AKAP, microtubule-associated protein-2, was characterized in 1984 (Lohmann et al., Proc. Natl. Acad. Sci. USA. 1984; 81:6723), more than 50 AKAPs that localize to various sub-cellular sites, including plasma membrane, actin cytoskeleton, nucleus, mitochondria, and endoplasmic reticulum, have been identified with diverse structures in species ranging from yeast to humans (Wong and Scott, Nat. Rev. Mol. Cell. Biol. 2004; 5:959). The AD of AKAPs for PKA is an amphipathic helix of 14-18 residues (Carr et al., J. Biol. Chem. 1991; 266:14188). The amino acid sequences of the AD are quite varied among individual AKAPs, with the binding affinities reported for RII dimers ranging from 2 to 90 nM (Alto et al., Proc. Natl. Acad. Sci. USA. 2003; 100:4445). AKAPs will only bind to dimeric R subunits. For human RIIα, the AD binds to a hydrophobic surface formed by the 23 amino-terminal residues (Colledge and Scott, Trends Cell Biol. 1999; 6:216). Thus, the dimerization domain and AKAP binding domain of human RIIα are both located within the same N-terminal 44 amino acid sequence (Newlon et al., Nat. Struct. Biol. 1999; 6:222; Newlon et al., EMBO J. 2001; 20:1651), which is termed the DDD herein.

We have developed a platform technology to utilize the DDD of human PKA regulatory subunit and the AD of AKAP as an excellent pair of linker modules for docking any two entities, referred to hereafter as A and B, into a noncovalent complex, which could be further locked into a stably tethered structure through the introduction of cysteine residues into both the DDD and AD at strategic positions to facilitate the formation of disulfide bonds. The general methodology of the “dock-and-lock” approach is as follows. Entity A is constructed by linking a DDD sequence to a precursor of A, resulting in a first component hereafter referred to as a. Because the DDD sequence would effect the spontaneous formation of a dimer, A would thus be composed of a₂. Entity B is constructed by linking an AD sequence to a precursor of B, resulting in a second component hereafter referred to as b. The dimeric motif of DDD contained in a₂ will create a docking site for binding to the AD sequence contained in b, thus facilitating a ready association of a₂ and b to form a binary, trimeric complex composed of a₂b. This binding event is made irreversible with a subsequent reaction to covalently secure the two entities via disulfide bridges, which occurs very efficiently based on the principle of effective local concentration because the initial binding interactions should bring the reactive thiol groups placed onto both the DDD and AD into proximity (Chmura et al., Proc. Natl. Acad. Sci. USA. 2001; 98:8480) to ligate site-specifically. Using various combinations of linkers, adaptor modules and precursors, a wide variety of DNL constructs of different stoichiometry may be produced and used, including but not limited to dimeric, trimeric, tetrameric, pentameric and hexameric DNL constructs (see, e.g., U.S. Pat. Nos. 7,550,143; 7,521,056; 7,534,866; 7,527,787 and 7,666,400.)

By attaching the DDD and AD away from the functional groups of the two precursors, such site-specific ligations are also expected to preserve the original activities of the two precursors. This approach is modular in nature and potentially can be applied to link, site-specifically and covalently, a wide range of substances, including peptides, proteins, antibodies, antibody fragments, and other effector moieties with a wide range of activities. Utilizing the fusion protein method of constructing AD and DDD conjugated effectors described in the Examples below, virtually any protein or peptide may be incorporated into a DNL construct. However, the technique is not limiting and other methods of conjugation may be utilized.

A variety of methods are known for making fusion proteins, including nucleic acid synthesis, hybridization and/or amplification to produce a synthetic double-stranded nucleic acid encoding a fusion protein of interest. Such double-stranded nucleic acids may be inserted into expression vectors for fusion protein production by standard molecular biology techniques (see, e.g. Sambrook et al., Molecular Cloning, A laboratory manual, 2^(nd) Ed, 1989). In such preferred embodiments, the AD and/or DDD moiety may be attached to either the N-terminal or C-terminal end of an effector protein or peptide. However, the skilled artisan will realize that the site of attachment of an AD or DDD moiety to an effector moiety may vary, depending on the chemical nature of the effector moiety and the part(s) of the effector moiety involved in its physiological activity. Site-specific attachment of a variety of effector moieties may be performed using techniques known in the art, such as the use of bivalent cross-linking reagents and/or other chemical conjugation techniques.

The skilled artisan will realize that the DNL technique may be utilized to produce complexes comprising multiple copies of the same anti-CD20 or anti-CD22 antibody, or to attach one or more anti-CD20 antibodies to one or more anti-CD22 antibodies, or to attach an anti-CD20 or anti-CD22 antibody to an antibody that binds to a different antigen expressed by B-cells. Alternatively, the DNL technique may be used to attach antibodies to different effector moieties, such as toxins, cytokines, carrier proteins for siRNA and other known effectors.

Structure-Function Relationships in AD and DDD Moieties

For different types of DNL constructs, different AD or DDD sequences may be utilized. Exemplary DDD and AD sequences are provided below.

DDD1 (SEQ ID NO: 13) SHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  DDD2 (SEQ ID NO: 14) CGHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  AD1 (SEQ ID NO: 15) QIEYLAKQIVDNAIQQA  AD2 (SEQ ID NO: 16) CGQIEYLAKQIVDNAIQQAGC 

The skilled artisan will realize that DDD1 and DDD2 are based on the DDD sequence of the human RIIα isoform of protein kinase A. However, in alternative embodiments, the DDD and AD moieties may be based on the DDD sequence of the human RIα form of protein kinase A and a corresponding AKAP sequence, as exemplified in DDD3, DDD3C and AD3 below.

DDD3 (SEQ ID NO: 17) SLRECELYVQKHNIQALLKDSIVQLCTARPERPMAFLREYFERLEKEEAK  DDD3C (SEQ ID NO: 18) MSCGGSLRECELYVQKHNIQALLKDSIVQLCTARPERPMAFLREYFERLE KEEAK AD3 (SEQ ID NO: 19) CGFEELAWKIAKMIWSDVFQQGC 

In other alternative embodiments, other sequence variants of AD and/or DDD moieties may be utilized in construction of the DNL complexes. For example, there are only four variants of human PKA DDD sequences, corresponding to the DDD moieties of PKA RIα, RIIα, RIβ and RIIβ. The RIIα DDD sequence is the basis of DDD1 and DDD2 disclosed above. The four human PKA DDD sequences are shown below. The DDD sequence represents residues 1-44 of RIIα, 1-44 of RIIβ, 12-61 of RIα and 13-66 of RIβ. (Note that the sequence of DDD1 is modified slightly from the human PKA RIIα DDD moiety.)

PKA RIα (SEQ ID NO: 20) SLRECELYVQKHNIQALLKDVSIVQLCTARPERPMAFLREYFEKLE  KEEAK PKA RIβ (SEQ ID NO: 21) SLKGCELYVQLHGIQQVLKDCIVHLCISKPERPMKFLREHFEKLEKEE NRQILA PKA RIIα (SEQ ID NO: 22) SHIQIPPGLTELLQGYTVEVGQQPPDLVDFAVEYFTRLREARRQ  PKA RIIβ (SEQ ID NO: 23) SIEIPAGLTELLQGFTVEVLRHQPADLLEFALQHFTRLQQENER 

The structure-function relationships of the AD and DDD domains have been the subject of investigation. (See, e.g., Burns-Hamuro et al., 2005, Protein Sci 14:2982-92; Carr et al., 2001, J Biol Chem 276:17332-38; Alto et al., 2003, Proc Natl Acad Sci USA 100:4445-50; Hundsrucker et al., 2006, Biochem J 396:297-306; Stokka et al., 2006, Biochem J 400:493-99; Gold et al., 2006, Mol Cell 24:383-95; Kinderman et al., 2006, Mol Cell 24:397-408, the entire text of each of which is incorporated herein by reference.)

For example, Kinderman et al. (2006, Mol Cell 24:397-408) examined the crystal structure of the AD-DDD binding interaction and concluded that the human DDD sequence contained a number of conserved amino acid residues that were important in either dimer formation or AKAP binding, underlined in SEQ ID NO:13 below. (See FIG. 1 of Kinderman et al., 2006, incorporated herein by reference.) The skilled artisan will realize that in designing sequence variants of the DDD sequence, one would desirably avoid changing any of the underlined residues, while conservative amino acid substitutions might be made for residues that are less critical for dimerization and AKAP binding. SHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA (SEQ ID NO:13)

As discussed in more detail below, conservative amino acid substitutions have been characterized for each of the twenty common L-amino acids. Thus, based on the data of Kinderman (2006) and conservative amino acid substitutions, potential alternative DDD sequences based on SEQ ID NO:13 are shown in Table 1. In devising Table 1, only highly conservative amino acid substitutions were considered. For example, charged residues were only substituted for residues of the same charge, residues with small side chains were substituted with residues of similar size, hydroxyl side chains were only substituted with other hydroxyls, etc. Because of the unique effect of proline on amino acid secondary structure, no other residues were substituted for proline. Even with such conservative substitutions, there are over twenty million possible alternative sequences for the 44 residue peptide (2×3×2×2×2×2×2×2×2×2×2×2×2×2×2×4×2×2×2×2×2×4×2×4). A limited number of such potential alternative DDD moiety sequences are shown in SEQ ID NO:24 to SEQ ID NO:43 below. The skilled artisan will realize that an almost unlimited number of alternative species within the genus of DDD moieties can be constructed by standard techniques, for example using a commercial peptide synthesizer or well known site-directed mutagenesis techniques. The effect of the amino acid substitutions on AD moiety binding may also be readily determined by standard binding assays, for example as disclosed in Alto et al. (2003, Proc Natl Acad Sci USA 100:4445-50).

TABLE 1 Conservative Amino Acid Substitutions in DDD1 (SEQ ID NO: 13). Consensus sequence disclosed as SEQ ID NO: 135. S H I Q I P P G L T E L L Q G Y T V E V L R T K   N       A   S D     N A   S   D     K R Q Q P P D L V E F A V E Y F T R L R E A R A N N     E     D   L   D     S K   K D L K L                   I                   I   I                   V                   V   V (SEQ ID NO: 24) THIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 25) SKIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 26) SRIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 27) SHINIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 28) SHIQIPPALTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 29) SHIQIPPGLSELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 30) SHIQIPPGLTDLLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 31) SHIQIPPGLTELLNGYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 32) SHIQIPPGLTELLQAYTVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 33) SHIQIPPGLTELLQGYSVEVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 34) SHIQIPPGLTELLQGYTVDVLRQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 35) SHIQIPPGLTELLQGYTVEVLKQQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 36) SHIQIPPGLTELLQGYTVEVLRNQPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 37) SHIQIPPGLTELLQGYTVEVLRQNPPDLVEFAVEYFTRLREARA  (SEQ ID NO: 38) SHIQIPPGLTELLQGYTVEVLRQQPPELVEFAVEYFTRLREARA  (SEQ ID NO: 39) SHIQIPPGLTELLQGYTVEVLRQQPPDLVDFAVEYFTRLREARA  (SEQ ID NO: 40) SHIQIPPGLTELLQGYTVEVLRQQPPDLVEFLVEYFTRLREARA  (SEQ ID NO: 41) SHIQIPPGLTELLQGYTVEVLRQQPPDLVEFIVEYFTRLREARA  (SEQ ID NO: 42) SHIQIPPGLTELLQGYTVEVLRQQPPDLVEFVVEYFTRLREARA  (SEQ ID NO: 43) SHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVDYFTRLREARA 

Alto et al. (2003, Proc Natl Acad Sci USA 100:4445-50) performed a bioinformatic analysis of the AD sequence of various AKAP proteins to design an RII selective AD sequence called AKAP-IS (SEQ ID NO:15), with a binding constant for DDD of 0.4 nM. The AKAP-IS sequence was designed as a peptide antagonist of AKAP binding to PKA. Residues in the AKAP-IS sequence where substitutions tended to decrease binding to DDD are underlined in SEQ ID NO:15 below. The skilled artisan will realize that in designing sequence variants of the AD sequence, one would desirably avoid changing any of the underlined residues, while conservative amino acid substitutions might be made for residues that are less critical for DDD binding. Table 2 shows potential conservative amino acid substitutions in the sequence of AKAP-IS (AD1, SEQ ID NO:15), similar to that shown for DDD1 (SEQ ID NO:13) in Table 1 above.

Even with such conservative substitutions, there are over thirty-five thousand possible alternative sequences for the 17 residue AD1 (SEQ ID NO:15) peptide sequence (2×3×2×4×3×2×2×2×2×2×2×4). A limited number of such potential alternative AD moiety sequences are shown in SEQ ID NO:44 to SEQ ID NO:61 below. Again, a very large number of species within the genus of possible AD moiety sequences could be made, tested and used by the skilled artisan, based on the data of Alto et al. (2003). It is noted that FIG. 2 of Alto (2003) shows an even large number of potential amino acid substitutions that may be made, while retaining binding activity to DDD moieties, based on actual binding experiments.

AKAP-IS (SEQ ID NO: 15) QIEYLAKQIVDNAIQQA 

TABLE 2 Conservative Amino Acid Substitutions in AD1 (SEQ ID NO: 15). Consensus sequence disclosed as SEQ ID NO: 136. Q I E Y L A K Q I V D N A I Q Q A N L D F I   R N     E Q     N N L   V   T V                       I       S                         V (SEQ ID NO: 44) NIEYLAKQIVDNAIQQA  (SEQ ID NO: 45) QLEYLAKQIVDNAIQQA  (SEQ ID NO: 46) QVEYLAKQIVDNAIQQA  (SEQ ID NO: 47) QIDYLAKQIVDNAIQQA  (SEQ ID NO: 48) QIEFLAKQIVDNAIQQA  (SEQ ID NO: 49) QIETLAKQIVDNAIQQA  (SEQ ID NO: 50) QIESLAKQIVDNAIQQA  (SEQ ID NO: 51) QIEYIAKQIVDNAIQQA  (SEQ ID NO: 52) QIEYVAKQIVDNAIQQA  (SEQ ID NO: 53) QIEYLARQIVDNAIQQA  (SEQ ID NO: 54) QIEYLAKNIVDNAIQQA  (SEQ ID NO: 55) QIEYLAKQIVENAIQQA  (SEQ ID NO: 56) QIEYLAKQIVDQAIQQA  (SEQ ID NO: 57) QIEYLAKQIVDNAINQA  (SEQ ID NO: 58) QIEYLAKQIVDNAIQNA  (SEQ ID NO: 59) QIEYLAKQIVDNAIQQL  (SEQ ID NO: 60) QIEYLAKQIVDNAIQQI  (SEQ ID NO: 61) QIEYLAKQIVDNAIQQV 

Gold et al. (2006, Mol Cell 24:383-95) utilized crystallography and peptide screening to develop a SuperAKAP-IS sequence (SEQ ID NO:62), exhibiting a five order of magnitude higher selectivity for the RII isoform of PKA compared with the RI isoform. Underlined residues indicate the positions of amino acid substitutions, relative to the AKAP-IS sequence, which increased binding to the DDD moiety of RIIα. In this sequence, the N-terminal Q residue is numbered as residue number 4 and the C-terminal A residue is residue number 20. Residues where substitutions could be made to affect the affinity for RIIα were residues 8, 11, 15, 16, 18, 19 and 20 (Gold et al., 2006). It is contemplated that in certain alternative embodiments, the SuperAKAP-IS sequence may be substituted for the AKAP-IS AD moiety sequence to prepare DNL constructs. Other alternative sequences that might be substituted for the AKAP-IS AD sequence are shown in SEQ ID NO:63-65. Substitutions relative to the AKAP-IS sequence are underlined. It is anticipated that, as with the AD2 sequence shown in SEQ ID NO:4, the AD moiety may also include the additional N-terminal residues cysteine and glycine and C-terminal residues glycine and cysteine.

SuperAKAP-IS (SEQ ID NO: 62) QIEYVAKQIVDYAIHQA  Alternative AKAP sequences (SEQ ID NO: 63) QIEYKAKQIVDHAIHQA  (SEQ ID NO: 64) QIEYHAKQIVDHAIHQA  (SEQ ID NO: 65) QIEYVAKQIVDHAIHQA 

FIG. 2 of Gold et al. disclosed additional DDD-binding sequences from a variety of AKAP proteins, shown below.

RII-Specific AKAPs AKAP-KL (SEQ ID NO: 66) PLEYQAGLLVQNAIQQAI  AKAP79 (SEQ ID NO: 67) LLIETASSLVKNAIQLSI  AKAP-Lbc (SEQ ID NO: 68) LIEEAASRIVDAVIEQVK  RI-Specific AKAPs AKAPce (SEQ ID NO: 69) ALYQFADRFSELVISEAL  RIAD (SEQ ID NO: 70) LEQVANQLADQIIKEAT  PV38 (SEQ ID NO: 71) FEELAWKIAKMIWSDVF  Dual-Specificity AKAPs AKAP7 (SEQ ID NO: 72) ELVRLSKRLVENAVLKAV  MAP2D (SEQ ID NO: 73) TAEEVSARIVQVVTAEAV  DAKAP1 (SEQ ID NO: 74) QIKQAAFQLISQVILEAT  DAKAP2 (SEQ ID NO: 75) LAWKIAKMIVSDVMQQ 

Stokka et al. (2006, Biochem J 400:493-99) also developed peptide competitors of AKAP binding to PKA, shown in SEQ ID NO:76-78. The peptide antagonists were designated as Ht31 (SEQ ID NO:76), RIAD (SEQ ID NO:77) and PV-38 (SEQ ID NO:78). The Ht-31 peptide exhibited a greater affinity for the RII isoform of PKA, while the RIAD and PV-38 showed higher affinity for RI.

Ht31 (SEQ ID NO: 76) DLIEEAASRIVDAVIEQVKAAGAY  RIAD (SEQ ID NO: 77) LEQYANQLADQIIKEATE  PV-38 (SEQ ID NO: 78) FEELAWKIAKMIWSDVFQQC 

Hundsrucker et al. (2006, Biochem J 396:297-306) developed still other peptide competitors for AKAP binding to PKA, with a binding constant as low as 0.4 nM to the DDD of the RII form of PKA. The sequences of various AKAP antagonistic peptides are provided in Table 1 of Hundsrucker et al., reproduced in Table 3 below. AKAPIS represents a synthetic RII subunit-binding peptide. All other peptides are derived from the RII-binding domains of the indicated AKAPs.

TABLE 3 AKAP Peptide sequences Peptide Sequence AKAPIS QIEYLAKQIVDNAIQQA  (SEQ ID NO: 15) AKAPIS-P QIEYLAKQIPDNAIQQA  (SEQ ID NO: 79) Ht31 KGADLIEEAASRIVDAVIEQVKAAG  (SEQ ID NO: 80) Ht31-P KGADLIEEAASRIPDAPIEQVKAAG  (SEQ ID NO: 81) AKAP7δ-wt-pep PEDAELVRLSKRLVENAVLKAVQQY  (SEQ ID NO: 82) AKAP7δ-L304T-pep PEDAELVRTSKRLVENAVLKAVQQY  (SEQ ID NO: 83) AKAP7δ-L308D-pep PEDAELVRLSKRDVENAVLKAVQQY  (SEQ ID NO: 84) AKAP7δ-P-pep PEDAELVRLSKRLPENAVLKAVQQY  (SEQ ID NO: 85) AKAP7δ-PP-pep PEDAELVRLSKRLPENAPLKAVQQY  (SEQ ID NO: 86) AKAP7δ-L314E-pep PEDAELVRLSKRLVENAVEKAVQQY  (SEQ ID NO: 87) AKAP1-pep EEGLDRNEEIKRAAFQIISQVISEA  (SEQ ID NO: 88) AKAP2-pep LVDDPLEYQAGLLVQNAIQQAIAEQ  (SEQ ID NO: 89) AKAP5-pep QYETLLIETASSLVKNAIQLSIEQL  (SEQ ID NO: 90) AKAP9-pep LEKQYQEQLEEEVAKVIVSMSIAFA  (SEQ ID NO: 91) AKAP10-pep NTDEAQEELAWKIAKMIVSDIMQQA  (SEQ ID NO: 92) AKAP11-pep VNLDKKAVLAEKIVAEAIEKAEREL  (SEQ ID NO: 93) AKAP12-pep NGILELETKSSKLVQNIIQTAVDQF  (SEQ ID NO: 94) AKAP14-pep TQDKNYEDELTQVALALVEDVINYA  (SEQ ID NO: 95) Rab32-pep ETSAKDNINIEEAARFLVEKILVNH  (SEQ ID NO: 96)

Residues that were highly conserved among the AD domains of different AKAP proteins are indicated below by underlining with reference to the AKAP IS sequence (SEQ ID NO:15). The residues are the same as observed by Alto et al. (2003), with the addition of the C-terminal alanine residue. (See FIG. 4 of Hundsrucker et al. (2006), incorporated herein by reference.) The sequences of peptide antagonists with particularly high affinities for the R11 DDD sequence were those of AKAP-IS, AKAP7δ-wt-pep, AKAP7δ-L304T-pep and AKAP7δ-L308D-pep.

AKAP-IS (SEQ ID NO: 15) QIEYLAKQIVDNAIQQA 

Can et al. (2001, J Biol Chem 276:17332-38) examined the degree of sequence homology between different AKAP-binding DDD sequences from human and non-human proteins and identified residues in the DDD sequences that appeared to be the most highly conserved among different DDD moieties. These are indicated below by underlining with reference to the human PKA RIIα DDD sequence of SEQ ID NO:13. Residues that were particularly conserved are further indicated by italics. The residues overlap with, but are not identical to those suggested by Kinderman et al. (2006) to be important for binding to AKAP proteins. The skilled artisan will realize that in designing sequence variants of DDD, it would be most preferred to avoid changing the most conserved residues (italicized), and it would be preferred to also avoid changing the conserved residues (underlined), while conservative amino acid substitutions may be considered for residues that are neither underlined nor italicized.

(SEQ ID NO: 13) SHIQ IP P GL TELLQGYT V EVLR Q QP P DLVEFA VE YF TR L REA R A 

A modified set of conservative amino acid substitutions for the DDD1 (SEQ ID NO:13) sequence, based on the data of Carr et al. (2001) is shown in Table 4. Even with this reduced set of substituted sequences, there are over 65,000 possible alternative DDD moiety sequences that may be produced, tested and used by the skilled artisan without undue experimentation. The skilled artisan could readily derive such alternative DDD amino acid sequences as disclosed above for Table 1 and Table 2.

TABLE 4 Conservative Amino Acid Substitutions in DDD1 (SEQ ID NO: 13). Consensus sequence disclosed as SEQ ID NO: 137. S H I Q I P P G L T E L L Q G Y T V E V L R T N S I L A Q Q P P D L V E F A V E Y F T R L R E A R A N I D S K K L L L I I A V V

The skilled artisan will realize that these and other amino acid substitutions in the DDD or AD amino acid sequences may be utilized to produce alternative species within the genus of AD or DDD moieties, using techniques that are standard in the field and only routine experimentation.

Amino Acid Substitutions

In various embodiments, the disclosed methods and compositions may involve production and use of proteins or peptides with one or more substituted amino acid residues. For example, the DDD and/or AD sequences used to make DNL constructs may be modified as discussed above.

The skilled artisan will be aware that, in general, amino acid substitutions typically involve the replacement of an amino acid with another amino acid of relatively similar properties (i.e., conservative amino acid substitutions). The properties of the various amino acids and effect of amino acid substitution on protein structure and function have been the subject of extensive study and knowledge in the art.

For example, the hydropathic index of amino acids may be considered (Kyte & Doolittle, 1982, J. Mol. Biol., 157:105-132). The relative hydropathic character of the amino acid contributes to the secondary structure of the resultant protein, which in turn defines the interaction of the protein with other molecules. Each amino acid has been assigned a hydropathic index on the basis of its hydrophobicity and charge characteristics (Kyte & Doolittle, 1982), these are: isoleucine (+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (−0.4); threonine (−0.7); serine (−0.8); tryptophan (−0.9); tyrosine (−1.3); proline (−1.6); histidine (−3.2); glutamate (−3.5); glutamine (−3.5); aspartate (−3.5); asparagine (−3.5); lysine (−3.9); and arginine (−4.5). In making conservative substitutions, the use of amino acids whose hydropathic indices are within ±2 is preferred, within ±1 are more preferred, and within ±0.5 are even more preferred.

Amino acid substitution may also take into account the hydrophilicity of the amino acid residue (e.g., U.S. Pat. No. 4,554,101). Hydrophilicity values have been assigned to amino acid residues: arginine (+3.0); lysine (+3.0); aspartate (+3.0); glutamate (+3.0); serine (+0.3); asparagine (+0.2); glutamine (+0.2); glycine (0); threonine (−0.4); proline (−0.5.+−.1); alanine (−0.5); histidine (−0.5); cysteine (−1.0); methionine (−1.3); valine (−1.5); leucine (−1.8); isoleucine (−1.8); tyrosine (−2.3); phenylalanine (−2.5); tryptophan (−3.4). Replacement of amino acids with others of similar hydrophilicity is preferred.

Other considerations include the size of the amino acid side chain. For example, it would generally not be preferred to replace an amino acid with a compact side chain, such as glycine or serine, with an amino acid with a bulky side chain, e.g., tryptophan or tyrosine. The effect of various amino acid residues on protein secondary structure is also a consideration. Through empirical study, the effect of different amino acid residues on the tendency of protein domains to adopt an alpha-helical, beta-sheet or reverse turn secondary structure has been determined and is known in the art (see, e.g., Chou & Fasman, 1974, Biochemistry, 13:222-245; 1978, Ann. Rev. Biochem., 47: 251-276; 1979, Biophys. J., 26:367-384).

Based on such considerations and extensive empirical study, tables of conservative amino acid substitutions have been constructed and are known in the art. For example: arginine and lysine; glutamate and aspartate; serine and threonine; glutamine and asparagine; and valine, leucine and isoleucine. Alternatively: Ala (A) leu, ile, val; Arg (R) gln, asn, lys; Asn (N) his, asp, lys, arg, gln; Asp (D) asn, glu; Cys (C) ala, ser; Gln (O) glu, asn; Glu (E) gln, asp; Gly (G) ala; His (H) asn, gln, lys, arg; Ile (I) val, met, ala, phe, leu; Leu (L) val, met, ala, phe, ile; Lys (K) gln, asn, arg; Met (M) phe, ile, leu; Phe (F) leu, val, ile, ala, tyr; Pro (P) ala; Ser (S), thr; Thr (T) ser; Trp (W) phe, tyr; Tyr (Y) trp, phe, thr, ser; Val (V) ile, leu, met, phe, ala.

Other considerations for amino acid substitutions include whether or not the residue is located in the interior of a protein or is solvent exposed. For interior residues, conservative substitutions would include: Asp and Asn; Ser and Thr; Ser and Ala; Thr and Ala; Ala and Gly; Ile and Val; Val and Leu; Leu and Ile; Leu and Met; Phe and Tyr; Tyr and Trp. (See, e.g., PROWL website at rockefeller.edu) For solvent exposed residues, conservative substitutions would include: Asp and Asn; Asp and Glu; Glu and Gln; Glu and Ala; Gly and Asn; Ala and Pro; Ala and Gly; Ala and Ser; Ala and Lys; Ser and Thr; Lys and Arg; Val and Leu; Leu and Ile; Ile and Val; Phe and Tyr. (Id.) Various matrices have been constructed to assist in selection of amino acid substitutions, such as the PAM250 scoring matrix, Dayhoff matrix, Grantham matrix, McLachlan matrix, Doolittle matrix, Henikoff matrix, Miyata matrix, Fitch matrix, Jones matrix, Rao matrix, Levin matrix and Risler matrix (Idem.)

In determining amino acid substitutions, one may also consider the existence of intermolecular or intramolecular bonds, such as formation of ionic bonds (salt bridges) between positively charged residues (e.g., His, Arg, Lys) and negatively charged residues (e.g., Asp, Glu) or disulfide bonds between nearby cysteine residues.

Methods of substituting any amino acid for any other amino acid in an encoded protein sequence are well known and a matter of routine experimentation for the skilled artisan, for example by the technique of site-directed mutagenesis or by synthesis and assembly of oligonucleotides encoding an amino acid substitution and splicing into an expression vector construct.

Preparation of Antibodies

The complexes described herein may comprise one or more monoclonal antibodies or fragments thereof. Rodent monoclonal antibodies to specific antigens may be obtained by methods known to those skilled in the art. (See, e.g., Kohler and Milstein, Nature 256: 495 (1975), and Coligan et al. (eds.), CURRENT PROTOCOLS IN IMMUNOLOGY, VOL. 1, pages 2.5.1-2.6.7 (John Wiley & Sons 1991)).

General techniques for cloning murine immunoglobulin variable domains have been disclosed, for example, by the publication of Orlandi et al., Proc. Nat'l Acad. Sci. USA 86: 3833 (1989). Techniques for constructing chimeric antibodies are well known to those of skill in the art. As an example, Leung et al., Hybridoma 13:469 (1994), disclose how they produced an LL2 chimera by combining DNA sequences encoding the V_(k) and V_(H) domains of LL2 monoclonal antibody, an anti-CD22 antibody, with respective human and IgG₁ constant region domains. This publication also provides the nucleotide sequences of the LL2 light and heavy chain variable regions, V_(k) and V_(H), respectively. Techniques for producing humanized antibodies are disclosed, for example, by Jones et al., Nature 321: 522 (1986), Riechmann et al., Nature 332: 323 (1988), Verhoeyen et al., Science 239: 1534 (1988), Carter et al., Proc. Nat'l Acad. Sci. USA 89: 4285 (1992), Sandhu, Crit. Rev. Biotech. 12: 437 (1992), and Singer et al., J. Immun. 150: 2844 (1993).

A chimeric antibody is a recombinant protein that contains the variable domains including the CDRs derived from one species of animal, such as a rodent antibody, while the remainder of the antibody molecule; i.e., the constant domains, is derived from a human antibody. Accordingly, a chimeric monoclonal antibody can also be humanized by replacing the sequences of the murine FR in the variable domains of the chimeric antibody with one or more different human FR. Specifically, mouse CDRs are transferred from heavy and light variable chains of the mouse immunoglobulin into the corresponding variable domains of a human antibody. As simply transferring mouse CDRs into human FRs often results in a reduction or even loss of antibody affinity, additional modification might be required in order to restore the original affinity of the murine antibody. This can be accomplished by the replacement of one or more some human residues in the FR regions with their murine counterparts to obtain an antibody that possesses good binding affinity to its epitope. (See, e.g., Tempest et al., Biotechnology 9:266 (1991) and Verhoeyen et al., Science 239: 1534 (1988)).

A fully human antibody can be obtained from a transgenic non-human animal. (See, e.g., Mendez et al., Nature Genetics, 15: 146-156, 1997; U.S. Pat. No. 5,633,425.) Methods for producing fully human antibodies using either combinatorial approaches or transgenic animals transformed with human immunoglobulin loci are known in the art (e.g., Mancini et al., 2004, New Microbiol. 27:315-28; Conrad and Scheller, 2005, Comb. Chem. High Throughput Screen. 8:117-26; Brekke and Loset, 2003, Curr. Opin. Pharmacol. 3:544-50; each incorporated herein by reference). Such fully human antibodies are expected to exhibit even fewer side effects than chimeric or humanized antibodies and to function in vivo as essentially endogenous human antibodies. In certain embodiments, the claimed methods and procedures may utilize human antibodies produced by such techniques.

In one alternative, the phage display technique may be used to generate human antibodies (e.g., Dantas-Barbosa et al., 2005, Genet. Mol. Res. 4:126-40, incorporated herein by reference). Human antibodies may be generated from normal humans or from humans that exhibit a particular disease state, such as a hematopoietic cancer (Dantas-Barbosa et al., 2005). The advantage to constructing human antibodies from a diseased individual is that the circulating antibody repertoire may be biased towards antibodies against disease-associated antigens.

In one non-limiting example of this methodology, Dantas-Barbosa et al. (2005) constructed a phage display library of human Fab antibody fragments from osteosarcoma patients. Generally, total RNA was obtained from circulating blood lymphocytes (Id.) Recombinant Fab were cloned from the μ, γ and κ chain antibody repertoires and inserted into a phage display library (Id.) RNAs were converted to cDNAs and used to make Fab cDNA libraries using specific primers against the heavy and light chain immunoglobulin sequences (Marks et al., 1991, J. Mol. Biol. 222:581-97). Library construction was performed according to Andris-Widhopf et al. (2000, In: Phage Display Laboratory Manual, Barbas et al. (eds), 1^(st) edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. pp. 9.1 to 9.22, incorporated herein by reference). The final Fab fragments were digested with restriction endonucleases and inserted into the bacteriophage genome to make the phage display library. Such libraries may be screened by standard phage display methods. The skilled artisan will realize that this technique is exemplary only and any known method for making and screening human antibodies or antibody fragments by phage display may be utilized.

In another alternative, transgenic animals that have been genetically engineered to produce human antibodies may be used to generate antibodies against essentially any immunogenic target, using standard immunization protocols as discussed above. Methods for obtaining human antibodies from transgenic mice are described by Green et al., Nature Genet. 7:13 (1994), Lonberg et al., Nature 368:856 (1994), and Taylor et al., Int. Immun. 6:579 (1994). A non-limiting example of such a system is the XENOMOUSE® (e.g., Green et al., 1999, J. Immunol. Methods 231:11-23, incorporated herein by reference) from Abgenix (Fremont, Calif.). In the XENOMOUSE® and similar animals, the mouse antibody genes have been inactivated and replaced by functional human antibody genes, while the remainder of the mouse immune system remains intact.

The XENOMOUSE® was transformed with germline-configured YACs (yeast artificial chromosomes) that contained portions of the human IgH and Ig kappa loci, including the majority of the variable region sequences, along accessory genes and regulatory sequences. The human variable region repertoire may be used to generate antibody producing B cells, which may be processed into hybridomas by known techniques. A XENOMOUSE® immunized with a target antigen will produce human antibodies by the normal immune response, which may be harvested and/or produced by standard techniques discussed above. A variety of strains of XENOMOUSE® are available, each of which is capable of producing a different class of antibody. Transgenically produced human antibodies have been shown to have therapeutic potential, while retaining the pharmacokinetic properties of normal human antibodies (Green et al., 1999). The skilled artisan will realize that the claimed compositions and methods are not limited to use of the XENOMOUSE® system but may utilize any transgenic animal that has been genetically engineered to produce human antibodies.

Known Antibodies

In various embodiments, the claimed methods and compositions may utilize any of a variety of antibodies known in the art. Antibodies of use may be commercially obtained from a number of known sources. For example, a variety of antibody secreting hybridoma lines are available from the American Type Culture Collection (ATCC, Manassas, Va.). A large number of antibodies against various disease targets have been deposited at the ATCC and/or have published variable region sequences and are available for use in the claimed methods and compositions. See, e.g., U.S. Pat. Nos. 7,312,318; 7,282,567; 7,151,164; 7,074,403; 7,060,802; 7,056,509; 7,049,060; 7,045,132; 7,041,803; 7,041,802; 7,041,293; 7,038,018; 7,037,498; 7,012,133; 7,001,598; 6,998,468; 6,994,976; 6,994,852; 6,989,241; 6,974,863; 6,965,018; 6,964,854; 6,962,981; 6,962,813; 6,956,107; 6,951,924; 6,949,244; 6,946,129; 6,943,020; 6,939,547; 6,921,645; 6,921,645; 6,921,533; 6,919,433; 6,919,078; 6,916,475; 6,905,681; 6,899,879; 6,893,625; 6,887,468; 6,887,466; 6,884,594; 6,881,405; 6,878,812; 6,875,580; 6,872,568; 6,867,006; 6,864,062; 6,861,511; 6,861,227; 6,861,226; 6,838,282; 6,835,549; 6,835,370; 6,824,780; 6,824,778; 6,812,206; 6,793,924; 6,783,758; 6,770,450; 6,767,711; 6,764,688; 6,764,681; 6,764,679; 6,743,898; 6,733,981; 6,730,307; 6,720,155; 6,716,966; 6,709,653; 6,693,176; 6,692,908; 6,689,607; 6,689,362; 6,689,355; 6,682,737; 6,682,736; 6,682,734; 6,673,344; 6,653,104; 6,652,852; 6,635,482; 6,630,144; 6,610,833; 6,610,294; 6,605,441; 6,605,279; 6,596,852; 6,592,868; 6,576,745; 6,572,856; 6,566,076; 6,562,618; 6,545,130; 6,544,749; 6,534,058; 6,528,625; 6,528,269; 6,521,227; 6,518,404; 6,511,665; 6,491,915; 6,488,930; 6,482,598; 6,482,408; 6,479,247; 6,468,531; 6,468,529; 6,465,173; 6,461,823; 6,458,356; 6,455,044; 6,455,040; 6,451,310; 6,444,206; 6,441,143; 6,432,404; 6,432,402; 6,419,928; 6,413,726; 6,406,694; 6,403,770; 6,403,091; 6,395,276; 6,395,274; 6,387,350; 6,383,759; 6,383,484; 6,376,654; 6,372,215; 6,359,126; 6,355,481; 6,355,444; 6,355,245; 6,355,244; 6,346,246; 6,344,198; 6,340,571; 6,340,459; 6,331,175; 6,306,393; 6,254,868; 6,187,287; 6,183,744; 6,129,914; 6,120,767; 6,096,289; 6,077,499; 5,922,302; 5,874,540; 5,814,440; 5,798,229; 5,789,554; 5,776,456; 5,736,119; 5,716,595; 5,677,136; 5,587,459; 5,443,953, 5,525,338, the Examples section of each of which is incorporated herein by reference. These are exemplary only and a wide variety of other antibodies and their hybridomas are known in the art. The skilled artisan will realize that antibody sequences or antibody-secreting hybridomas against almost any disease-associated antigen may be obtained by a simple search of the ATCC, NCBI and/or USPTO databases for antibodies against a selected disease-associated target of interest. The antigen binding domains of the cloned antibodies may be amplified, excised, ligated into an expression vector, transfected into an adapted host cell and used for protein production, using standard techniques well known in the art.

Exemplary known antibodies that may be of use for therapy of cancer or autoimmune disease within the scope of the claimed methods and compositions include, but are not limited to, LL1 (anti-CD74), LL2 and RFB4 (anti-CD22), RS7 (anti-epithelial glycoprotein-1 (EGP-1)), PAM4 and KC4 (both anti-mucin), MN-14 (anti-carcinoembryonic antigen (CEA or CEACAM5, also known as CD66e)), Mu-9 (anti-colon-specific antigen-p), Immu-31 (an anti-alpha-fetoprotein), TAG-72 (e.g., CC49), Tn, J591 or HuJ591 (anti-PSMA (prostate-specific membrane antigen)), AB-PG1-XG1-026 (anti-PSMA dimer), D2/B (anti-PSMA), G250 (an anti-carbonic anhydrase IX MAb), hL243 (anti-HLA-DR), R1 (anti-IGF-1R), A20 (anti-CD20), A19 (anti-CD19), MN-3 or MN-15 (anti-CEACAM6). Such antibodies are known in the art (e.g., U.S. Pat. Nos. 5,686,072; 5,874,540; 6,107,090; 6,183,744; 6,306,393; 6,653,104; 6,730.300; 6,899,864; 6,926,893; 6,962,702; 7,074,403; 7,230,084; 7,238,785; 7,238,786; 7,256,004; 7,282,567; 7,300,655; 7,312,318; 7,585,491; 7,612,180; 7,642,239; and U.S. Patent Application Publ. No. 20040202666 (now abandoned); 20050271671; and 20060193865; the Examples section of each incorporated herein by reference.) Specific known antibodies of use include, but are not limited to, hPAM4 (U.S. Pat. No. 7,282,567), hA20 (U.S. Pat. No. 7,251,164), hA19 (U.S. Pat. No. 7,109,304), hIMMU31 (U.S. Pat. No. 7,300,655), hLL1 (U.S. Pat. No. 7,312,318), hLL2 (U.S. Pat. No. 7,074,403), hMu-9 (U.S. Pat. No. 7,387,773), hL243 (U.S. Pat. No. 7,612,180), hMN-14 (U.S. Pat. No. 6,676,924), hMN-15 (U.S. Pat. No. 7,541,440), hR1 (U.S. patent application Ser. No. 12/689,336), hRS7 (U.S. Pat. No. 7,238,785), hMN-3 (U.S. Pat. No. 7,541,440), AB-PG1-XG1-026 (U.S. patent application Ser. No. 11/983,372, deposited as ATCC PTA-4405 and PTA-4406) and D2/B (WO 2009/130575). Other known antibodies are disclosed, for example, in U.S. Pat. Nos. 5,686,072; 5,874,540; 6,107,090; 6,183,744; 6,306,393; 6,653,104; 6,730,300; 6,899,864; 6,926,893; 6,962,702; 7,074,403; 7,230,084; 7,238,785; 7,238,786; 7,256,004; 7,282,567; 7,300,655; 7,312,318; 7,585,491; 7,612,180; 7,642,239; and U.S. Patent Application Publ. No. 20040202666 (now abandoned); 20050271671; and 20060193865. The text of each recited patent or application is incorporated herein by reference with respect to the Figures and Examples sections.

Antibody Fragments

Antibody fragments which recognize specific epitopes can be generated by known techniques. The antibody fragments are antigen binding portions of an antibody, such as F(ab)₂, Fab′, Fab, Fv, scFv and the like. Other antibody fragments include, but are not limited to, F(ab′)₂ fragments which can be produced by pepsin digestion of the antibody molecule and Fab′ fragments which can be generated by reducing disulfide bridges of the F(ab′)₂ fragments. Alternatively, Fab′ expression libraries can be constructed (Huse et al., 1989, Science, 246:1274-1281) to allow rapid and easy identification of monoclonal Fab′ fragments with the desired specificity.

A single chain Fv molecule (scFv) comprises a VL domain and a VH domain. The VL and VH domains associate to form a target binding site. These two domains are further covalently linked by a peptide linker (L). Methods for making scFv molecules and designing suitable peptide linkers are disclosed in U.S. Pat. No. 4,704,692, U.S. Pat. No. 4,946,778, R. Raag and M. Whitlow, “Single Chain Fvs.” FASEB Vol 9:73-80 (1995) and R. E. Bird and B. W. Walker, “Single Chain Antibody Variable Regions,” TIBTECH, Vol 9: 132-137 (1991).

An antibody fragment can be prepared by known methods, for example, as disclosed by Goldenberg, U.S. Pat. Nos. 4,036,945 and 4,331,647 and references contained therein. Also, see Nisonoff et al., Arch Biochem. Biophys. 89: 230 (1960); Porter, Biochem. J. 73: 119 (1959), Edelman et al., in METHODS IN ENZYMOLOGY VOL. 1, page 422 (Academic Press 1967), and Coligan at pages 2.8.1-2.8.10 and 2.10.-2.10.4.

A single complementarity-determining region (CDR) is a segment of the variable region of an antibody that is complementary in structure to the epitope to which the antibody binds and is more variable than the rest of the variable region. Accordingly, a CDR is sometimes referred to as hypervariable region. A variable region comprises three CDRs. CDR peptides can be obtained by constructing genes encoding the CDR of an antibody of interest. Such genes are prepared, for example, by using the polymerase chain reaction to synthesize the variable region from RNA of antibody-producing cells. (See, e.g., Larrick et al., Methods: A Companion to Methods in Enzymology 2: 106 (1991); Courtenay-Luck, “Genetic Manipulation of Monoclonal Antibodies,” in MONOCLONAL ANTIBODIES: PRODUCTION, ENGINEERING AND CLINICAL APPLICATION, Ritter et al. (eds.), pages 166-179 (Cambridge University Press 1995); and Ward et al., “Genetic Manipulation and Expression of Antibodies,” in MONOCLONAL ANTIBODIES: PRINCIPLES AND APPLICATIONS, Birch et al., (eds.), pages 137-185 (Wiley-Liss, Inc. 1995).

Another form of an antibody fragment is a single-domain antibody (dAb), sometimes referred to as a single chain antibody. Techniques for producing single-domain antibodies are well known in the art (see, e.g., Cossins et al., Protein Expression and Purification, 2007, 51:253-59; Shuntao et al., Molec Immunol 2006, 43:1912-19; Tanha et al., J. Biol. Chem. 2001, 276:24774-780). Single domain antibodies may be obtained, for example, from camels, alpacas or llamas by standard immunization techniques. (See, e.g., Muyldermans et al., TIBS 26:230-235, 2001; Yau et al., J Immunol Methods 281:161-75, 2003; Maass et al., J Immunol Methods 324:13-25, 2007). They can have potent antigen-binding capacity and can interact with novel epitopes that are inaccessible to conventional V_(H)-V_(L) pairs. (Muyldermans et al., 2001). Alpaca serum IgG contains about 50% camelid heavy chain only IgG antibodies (HCAbs) (Maass et al., 2007). Alpacas may be immunized with known antigens, such as TNF-α, and single domain antibodies can be isolated that bind to and neutralize the target antigen (Maass et al., 2007). PCR primers that amplify virtually all alpaca antibody coding sequences have been identified and may be used to construct single domain phage display libraries, which can be used for antibody fragment isolation by standard biopanning techniques well known in the art (Maass et al., 2007).

In certain embodiments, the sequences of antibodies or antibody fragments, such as the Fc portions of antibodies, may be varied to optimize their physiological characteristics, such as the half-life in serum. Methods of substituting amino acid sequences in proteins are widely known in the art, such as by site-directed mutagenesis (e.g. Sambrook et al., Molecular Cloning, A laboratory manual, 2^(nd) Ed, 1989). In preferred embodiments, the variation may involve the addition or removal of one or more glycosylation sites in the Fc sequence (e.g., U.S. Pat. No. 6,254,868, the Examples section of which is incorporated herein by reference). In other preferred embodiments, specific amino acid substitutions in the Fc sequence may be made (e.g., Hornick et al., 2000, J Nucl Med 41:355-62; Hinton et al., 2006, J Immunol 176:346-56; Petkova et al. 2006, Int Immunol 18:1759-69; U.S. Pat. No. 7,217,797).

Multispecific and Multivalent Antibodies

Various embodiments may concern use of multispecific and/or multivalent antibodies. For example, an anti-CD20 antibody or fragment thereof and an anti-CD22 antibody or fragment thereof may be joined together by means such as the dock-and-lock technique described above. Other combinations of antibodies or fragments thereof may be utilized. For example, the anti-CD20 or anti-CD22 antibody could be combined with another antibody against a different epitope of the same antigen, or alternatively with an antibody against another antigen, such as CD4, CD5, CD8, CD14, CD15, CD19, CD20, CD21, CD22, CD23, CD25, CD33, CD37, CD38, CD40, CD40L, CD46, CD52, CD54, CD74, CD80, CD126, CD138, B7, HM1.24, HLA-DR, an angiogenesis factor, tenascin, VEGF, P1GF, ED-B fibronectin, an oncogene, an oncogene product, NCA 66a-d, necrosis antigens, Ii, IL-2, T101, TAC, IL-6, MUC-1, TRAIL-R1 (DR4) or TRAIL-R2 (DR5).

Methods for producing bispecific antibodies include engineered recombinant antibodies which have additional cysteine residues so that they crosslink more strongly than the more common immunoglobulin isotypes. (See, e.g., FitzGerald et al, Protein Eng 10:1221-1225, 1997). Another approach is to engineer recombinant fusion proteins linking two or more different single-chain antibody or antibody fragment segments with the needed dual specificities. (See, e.g., Coloma et al., Nature Biotech. 15:159-163, 1997). A variety of bispecific antibodies can be produced using molecular engineering. In one form, the bispecific antibody may consist of, for example, a scFv with a single binding site for one antigen and a Fab fragment with a single binding site for a second antigen. In another form, the bispecific antibody may consist of, for example, an IgG with two binding sites for one antigen and two scFv with two binding sites for a second antigen.

Immunoconitmates

In preferred embodiments, an antibody or antibody fragment in a DNL complex may be directly attached to one or more therapeutic agents to form an immunoconjugate. Therapeutic agents may be attached, for example to reduced SH groups and/or to carbohydrate side chains. A therapeutic agent can be attached at the hinge region of a reduced antibody component via disulfide bond formation. Alternatively, such agents can be attached using a heterobifunctional cross-linker, such as N-succinyl 3-(2-pyridyldithio)propionate (SPDP). Yu et al., Int. J. Cancer 56: 244 (1994). General techniques for such conjugation are well-known in the art. See, for example, Wong, CHEMISTRY OF PROTEIN CONJUGATION AND CROSS-LINKING (CRC Press 1991); Upeslacis et al., “Modification of Antibodies by Chemical Methods,” in MONOCLONAL ANTIBODIES: PRINCIPLES AND APPLICATIONS, Birch et al. (eds.), pages 187-230 (Wiley-Liss, Inc. 1995); Price, “Production and Characterization of Synthetic Peptide-Derived Antibodies,” in MONOCLONAL ANTIBODIES: PRODUCTION, ENGINEERING AND CLINICAL APPLICATION, Ritter et al. (eds.), pages 60-84 (Cambridge University Press 1995). Alternatively, the therapeutic agent can be conjugated via a carbohydrate moiety in the Fc region of the antibody.

Methods for conjugating functional groups to antibodies via an antibody carbohydrate moiety are well-known to those of skill in the art. See, for example, Shih et al., Int. J. Cancer 41: 832 (1988); Shih et al., Int. J. Cancer 46: 1101 (1990); and Shih et al., U.S. Pat. No. 5,057,313, the Examples section of which is incorporated herein by reference. The general method involves reacting an antibody having an oxidized carbohydrate portion with a carrier polymer that has at least one free amine function. This reaction results in an initial Schiff base (imine) linkage, which can be stabilized by reduction to a secondary amine to form the final conjugate.

The Fc region may be absent if the antibody component of the immunoconjugate is an antibody fragment. However, it is possible to introduce a carbohydrate moiety into the light chain variable region of a full length antibody or antibody fragment. See, for example, Leung et al., J. Immunol. 154: 5919 (1995); U.S. Pat. Nos. 5,443,953 and 6,254,868, the Examples section of which is incorporated herein by reference. The engineered carbohydrate moiety is used to attach the therapeutic or diagnostic agent.

An alternative method for attaching therapeutic agents to an antibody or fragment involves use of click chemistry reactions. The click chemistry approach was originally conceived as a method to rapidly generate complex substances by joining small subunits together in a modular fashion. (See, e.g., Kolb et al., 2004, Angew Chem Int Ed 40:3004-31; Evans, 2007, Aust J Chem 60:384-95.) Various forms of click chemistry reaction are known in the art, such as the Huisgen 1,3-dipolar cycloaddition copper catalyzed reaction (Tornoe et al., 2002, J Organic Chem 67:3057-64), which is often referred to as the “click reaction.” Other alternatives include cycloaddition reactions such as the Diels-Alder, nucleophilic substitution reactions (especially to small strained rings like epoxy and aziridine compounds), carbonyl chemistry formation of urea compounds and reactions involving carbon-carbon double bonds, such as alkynes in thiol-yne reactions.

The azide alkyne Huisgen cycloaddition reaction uses a copper catalyst in the presence of a reducing agent to catalyze the reaction of a terminal alkyne group attached to a first molecule. In the presence of a second molecule comprising an azide moiety, the azide reacts with the activated alkyne to form a 1,4-disubstituted 1,2,3-triazole. The copper catalyzed reaction occurs at room temperature and is sufficiently specific that purification of the reaction product is often not required. (Rostovstev et al., 2002, Angew Chem Int Ed 41:2596; Tornoe et al., 2002, J Org Chem 67:3057.) The azide and alkyne functional groups are largely inert towards biomolecules in aqueous medium, allowing the reaction to occur in complex solutions. The triazole formed is chemically stable and is not subject to enzymatic cleavage, making the click chemistry product highly stable in biological systems. Although the copper catalyst is toxic to living cells, the copper-based click chemistry reaction may be used in vitro for immunoconjugate formation.

A copper-free click reaction has been proposed for covalent modification of biomolecules. (See, e.g., Agard et al., 2004, J Am Chem Soc 126:15046-47.) The copper-free reaction uses ring strain in place of the copper catalyst to promote a [3+2] azide-alkyne cycloaddition reaction (Id.) For example, cyclooctyne is an 8-carbon ring structure comprising an internal alkyne bond. The closed ring structure induces a substantial bond angle deformation of the acetylene, which is highly reactive with azide groups to form a triazole. Thus, cyclooctyne derivatives may be used for copper-free click reactions (Id.)

Another type of copper-free click reaction was reported by Ning et al. (2010, Angew Chem Int Ed 49:3065-68), involving strain-promoted alkyne-nitrone cycloaddition. To address the slow rate of the original cyclooctyne reaction, electron-withdrawing groups are attached adjacent to the triple bond (Id.) Examples of such substituted cyclooctynes include difluorinated cyclooctynes, 4-dibenzocyclooctynol and azacyclooctyne (Id.) An alternative copper-free reaction involved strain-promoted akyne-nitrone cycloaddition to give N-alkylated isoxazolines (Id.) The reaction was reported to have exceptionally fast reaction kinetics and was used in a one-pot three-step protocol for site-specific modification of peptides and proteins (Id.) Nitrones were prepared by the condensation of appropriate aldehydes with N-methylhydroxylamine and the cycloaddition reaction took place in a mixture of acetonitrile and water (Id.) These and other known click chemistry reactions may be used to attach therapeutic agents to antibodies in vitro.

The specificity of the click chemistry reaction may be used as a substitute for the antibody-hapten binding interaction used in pretargeting with bispecific antibodies. In this alternative embodiment, the specific reactivity of e.g., cyclooctyne moieties for azide moieties or alkyne moieties for nitrone moieties may be used in an in vivo cycloaddition reaction. An antibody-based DNL complex is activated by incorporation of a substituted cyclooctyne, an azide or a nitrone moiety. A targetable construct is labeled with one or more diagnostic or therapeutic agents and a complementary reactive moiety. I.e., where the antibody comprises a cyclooctyne, the targetable construct will comprise an azide; where the antibody comprises a nitrone, the targetable construct will comprise an alkyne, etc. The DNL complex comprising an activated antibody or fragment is administered to a subject and allowed to localize to a targeted cell, tissue or pathogen, as disclosed for pretargeting protocols. The reactive labeled targetable construct is then administered. Because the cyclooctyne, nitrone or azide on the targetable construct is unreactive with endogenous biomolecules and highly reactive with the complementary moiety on the antibody, the specificity of the binding interaction results in the highly specific binding of the targetable construct to the tissue-localized antibody.

Therapeutic Agents

A wide variety of therapeutic reagents can be administered concurrently or sequentially with the subject DNL complexes. For example, drugs, toxins, oligonucleotides, immunomodulators, hormones, hormone antagonists, enzymes, enzyme inhibitors, radionuclides, angiogenesis inhibitors, other antibodies or fragments thereof, etc. The therapeutic agents recited here are those agents that also are useful for administration separately with an antibody or fragment thereof as described above. Therapeutic agents include, for example, cytotoxic agents such as vinca alkaloids, anthracyclines, gemcitabine, epipodophyllotoxins, taxanes, antimetabolites, alkylating agents, antibiotics, SN-38, COX-2 inhibitors, antimitotics, anti-angiogenic and pro-apoptotic agents, particularly doxorubicin, methotrexate, taxol, CPT-11, camptothecans, proteosome inhibitors, mTOR inhibitors, HDAC inhibitors, tyrosine kinase inhibitors, and others.

Other useful cytotoxic agents include nitrogen mustards, alkyl sulfonates, nitrosoureas, triazenes, folic acid analogs, COX-2 inhibitors, antimetabolites, pyrimidine analogs, purine analogs, platinum coordination complexes, mTOR inhibitors, tyrosine kinase inhibitors, proteosome inhibitors, HDAC inhibitors, camptothecins, hormones, and the like. Suitable cytotoxic agents are described in REMINGTON'S PHARMACEUTICAL SCIENCES, 19th Ed. (Mack Publishing Co. 1995), and in GOODMAN AND GILMAN'S THE PHARMACOLOGICAL BASIS OF THERAPEUTICS, 7th Ed. (MacMillan Publishing Co. 1985), as well as revised editions of these publications.

In a preferred embodiment, conjugates of camptothecins and related compounds, such as SN-38, may be conjugated to an anti-CD20 or anti-CD22 antibody, for example as disclosed in U.S. Pat. No. 7,591,994, the Examples section of which is incorporated herein by reference.

The therapeutic agent may be selected from the group consisting of aplidin, azaribine, anastrozole, azacytidine, bleomycin, bortezomib, bryostatin-1, busulfan, calicheamycin, camptothecin, 10-hydroxycamptothecin, carmustine, celebrex, chlorambucil, cisplatin, irinotecan (CPT-11), SN-38, carboplatin, cladribine, cyclophosphamide, cytarabine, dacarbazine, docetaxel, dactinomycin, daunomycin glucuronide, daunorubicin, dexamethasone, diethylstilbestrol, doxorubicin, doxorubicin glucuronide, epirubicin glucuronide, ethinyl estradiol, estramustine, etoposide, etoposide glucuronide, etoposide phosphate, floxuridine (FUdR), 3′,5′-O-dioleoyl-FudR (FUdR-dO), fludarabine, flutamide, fluorouracil, fluoxymesterone, gemcitabine, hydroxyprogesterone caproate, hydroxyurea, idarubicin, ifosfamide, L-asparaginase, leucovorin, lomustine, mechlorethamine, medroprogesterone acetate, egestrol acetate, melphalan, mercaptopurine, 6-mercaptopurine, methotrexate, mitoxantrone, mithramycin, mitomycin, mitotane, phenyl butyrate, prednisone, procarbazine, paclitaxel, pentostatin, PSI-341, semustine streptozocin, tamoxifen, taxanes, taxol, testosterone propionate, thalidomide, thioguanine, thiotepa, teniposide, topotecan, uracil mustard, velcade, vinblastine, vinorelbine, vincristine, ricin, abrin, ribonuclease, onconase, rapLR1, DNase I, Staphylococcal enterotoxin-A, pokeweed antiviral protein, gelonin, diphtheria toxin, Pseudomonas exotoxin, and Pseudomonas endotoxin.

A toxin can be of animal, plant or microbial origin. A toxin, such as Pseudomonas exotoxin, may also be complexed to or form the therapeutic agent portion of an immunoconjugate. Other toxins include ricin, abrin, ribonuclease (RNase), DNase I, Staphylococcal enterotoxin-A, pokeweed antiviral protein, onconase, gelonin, diphtheria toxin, Pseudomonas exotoxin, and Pseudomonas endotoxin. See, for example, Pastan et al., Cell 47:641 (1986), Goldenberg, C A—A Cancer Journal for Clinicians 44:43 (1994), Sharkey and Goldenberg, C A—A Cancer Journal for Clinicians 56:226 (2006). Additional toxins suitable for use are known to those of skill in the art and are disclosed in U.S. Pat. No. 6,077,499, the Examples section of which is incorporated herein by reference.

The therapeutic agent may be an enzyme selected from the group consisting of malate dehydrogenase, staphylococcal nuclease, delta-V-steroid isomerase, yeast alcohol dehydrogenase, alpha-glycerophosphate dehydrogenase, triose phosphate isomerase, horseradish peroxidase, alkaline phosphatase, asparaginase, glucose oxidase, beta-galactosidase, ribonuclease, urease, catalase, glucose-6-phosphate dehydrogenase, glucoamylase and acetylcholinesterase.

As used herein, the term “immunomodulator” includes cytokines, lymphokines, monokines, stem cell growth factors, lymphotoxins, hematopoietic factors, colony stimulating factors (CSF), interferons (IFN), parathyroid hormone, thyroxine, insulin, proinsulin, relaxin, prorelaxin, follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), luteinizing hormone (LH), hepatic growth factor, prostaglandin, fibroblast growth factor, prolactin, placental lactogen, OB protein, transforming growth factor (TGF), TGF-α, TGF-β, insulin-like growth factor (IGF), erythropoietin, thrombopoietin, tumor necrosis factor (TNF), TNF-α, TNF-β, mullerian-inhibiting substance, mouse gonadotropin-associated peptide, inhibin, activin, vascular endothelial growth factor, integrin, interleukin (IL), granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF), interferon-α, interferon-β, interferon-γ, S1 factor, IL-1, IL-1cc, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-14, IL-15, IL-16, IL-17, IL-18 IL-21, IL-25, LIF, kit-ligand, FLT-3, angiostatin, thrombospondin, endostatin, LT, and the like.

Exemplary anti-angiogenic agents may include angiostatin, endostatin, vasculostatin, canstatin, maspin, anti-VEGF binding molecules, anti-placental growth factor binding molecules, or anti-vascular growth factor binding molecules.

In certain embodiments, the DNL complex may comprise one or more chelating moieties, such as NOTA, DOTA, DTPA, TETA, Tscg-Cys, or Tsca-Cys. In certain embodiments, the chelating moiety may form a complex with a therapeutic or diagnostic cation, such as Group II, Group III, Group IV, Group V, transition, lanthanide or actinide metal cations, Tc, Re, Bi, Cu, As, Ag, Au, At, or Pb.

The antibody or fragment thereof may be administered as an immunoconjugate comprising one or more radioactive isotopes useful for treating diseased tissue. Particularly useful therapeutic radionuclides include, but are not limited to ¹¹¹In, ¹⁷⁷Lu, ²¹²Bi, ²¹³Bi, ²¹¹At, ⁶²Cu, ⁶⁴Cu, ⁶⁷Cu, ⁹⁰Y, ¹²⁵I, ¹³¹I, ³²P, ³³P, ⁴⁷Sc, ¹¹¹Ag, ⁶⁷Ga, ¹⁴²Pr, ¹⁵³Sm, ¹⁶¹Tb, ¹⁶⁶Dy, ¹⁶⁶Ho, ¹⁸⁶Re, ¹⁸⁸Re, ¹⁸⁹Re, ²¹²Pb, ²²³Ra, ²²⁵Ac, ⁵⁹Fe, ⁷⁵Se, ⁷⁷As, ⁸⁹Sr, ⁹⁹Mo, ¹⁰⁵Rh, ¹⁰⁹Pd, ¹⁴³Pr, ¹⁴⁹Pm, ¹⁶⁹Er, ¹⁹⁴Ir, ¹⁹⁸Au, ¹⁹⁹Au, and ²¹¹Pb. The therapeutic radionuclide preferably has a decay energy in the range of 20 to 6,000 keV, preferably in the ranges 60 to 200 keV for an Auger emitter, 100-2,500 keV for a beta emitter and 4,000-6,000 keV for an alpha emitter. Maximum decay energies of useful beta-particle-emitting nuclides are preferably 20-5,000 keV, more preferably 100-4,000 keV and most preferably 500-2,500 keV. Also preferred are radionuclides that substantially decay with Auger-emitting particles. For example, Co-58, Ga-67, Br-80m, Tc-99m, Rh-103m, Pt-109, In-111, Sb-119, I-125, Ho-161, Os-189m and Ir-192. Decay energies of useful beta-particle-emitting nuclides are preferably <1,000 keV, more preferably <100 keV, and most preferably <70 keV. Also preferred are radionuclides that substantially decay with generation of alpha-particles. Such radionuclides include, but are not limited to: Dy-152, At-211, Bi-212, Ra-223, Rn-219, Po-215, Bi-211, Ac-225, Fr-221, At-217, Bi-213 and Fm-255. Decay energies of useful alpha-particle-emitting radionuclides are preferably 2,000-10,000 keV, more preferably 3,000-8,000 keV, and most preferably 4,000-7,000 keV.

Additional potential therapeutic radioisotopes include ¹¹C, ¹³N, ¹⁵O, ⁷⁵Br, ¹⁹⁸Au, ²²⁴Ac, ¹²⁶I, ¹³³I, ⁷⁷Br, ^(113m)In, ⁹⁵Ru, ⁹⁷Ru, ¹⁰³Ru, ¹⁰⁵Ru, ¹⁰⁷Hg, ²⁰³Hg, ^(121m)Te, ^(122m)Te, ^(125m)Te, ¹⁶⁵Tm, ¹⁶⁷Tm, ¹⁶⁸Tm, ¹⁹⁷Pt, ¹⁰⁹Pd, ¹⁰⁵Rh, ¹⁴²Pr, ¹⁴³Pr, ¹⁶¹Tb, ¹⁶⁶Ho, ¹⁹⁹Au, ⁵⁷Co, ⁵⁸Co, ⁵¹Cr, ⁵⁹Fe, ⁷⁵Se, ²⁰¹Tl, ²²⁵Ac, ⁷⁶Br, ¹⁶⁹Yb, and the like.

Interference RNA

In certain preferred embodiments the therapeutic agent may be a siRNA or interference RNA species. The siRNA, interference RNA or therapeutic gene may be attached to a carrier moiety that is conjugated to an antibody or fragment thereof. A variety of carrier moieties for siRNA have been reported and any such known carrier may be incorporated into a therapeutic antibody for use. Non-limiting examples of carriers include protamine (Rossi, 2005, Nat Biotech 23:682-84; Song et al., 2005, Nat Biotech 23:709-17); dendrimers such as PAMAM dendrimers (Pan et al., 2007, Cancer Res. 67:8156-8163); polyethylenimine (Schiffelers et al., 2004, Nucl Acids Res 32:e149); polypropyleneimine (Taratula et al., 2009, J Control Release 140:284-93); polylysine (Inoue et al., 2008, J Control Release 126:59-66); histidine-containing reducible polycations (Stevenson et al., 2008, J Control Release 130:46-56); histone H1 protein (Haberland et al., 2009, Mol Biol Rep 26:1083-93); cationic comb-type copolymers (Sato et al., 2007, J Control Release 122:209-16); polymeric micelles (U.S. Patent Application Publ. No. 20100121043); and chitosan-thiamine pyrophosphate (Rojanarata et al., 2008, Pharm Res 25:2807-14). The skilled artisan will realize that in general, polycationic proteins or polymers are of use as siRNA carriers. The skilled artisan will further realize that siRNA carriers can also be used to carry other oligonucleotide or nucleic acid species, such as anti-sense oligonucleotides or short DNA genes.

Known siRNA species of potential use include those specific for IKK-gamma (U.S. Pat. No. 7,022,828); VEGF, Flt-1 and Flk-1/KDR (U.S. Pat. No. 7,148,342); Bc12 and EGFR (U.S. Pat. No. 7,541,453); CDC20 (U.S. Pat. No. 7,550,572); transducin (beta)-like 3 (U.S. Pat. No. 7,576,196); K-ras (U.S. Pat. No. 7,576,197); carbonic anhydrase II (U.S. Pat. No. 7,579,457); complement component 3 (U.S. Pat. No. 7,582,746); interleukin-1 receptor-associated kinase 4 (IRAK4) (U.S. Pat. No. 7,592,443); survivin (U.S. Pat. No. 7,608,707); superoxide dismutase 1 (U.S. Pat. No. 7,632,938); MET proto-oncogene (U.S. Pat. No. 7,632,939); amyloid beta precursor protein (APP) (U.S. Pat. No. 7,635,771); IGF-1R (U.S. Pat. No. 7,638,621); ICAM1 (U.S. Pat. No. 7,642,349); complement factor B (U.S. Pat. No. 7,696,344); p53 (U.S. Pat. No. 7,781,575), and apolipoprotein B (U.S. Pat. No. 7,795,421), the Examples section of each referenced patent incorporated herein by reference.

Additional siRNA species are available from known commercial sources, such as Sigma-Aldrich (St Louis, Mo.), Invitrogen (Carlsbad, Calif.), Santa Cruz Biotechnology (Santa Cruz, Calif.), Ambion (Austin, Tex.), Dharmacon (Thermo Scientific, Lafayette, Colo.), Promega (Madison, Wis.), Minis Bio (Madison, Wis.) and Qiagen (Valencia, Calif.), among many others. Other publicly available sources of siRNA species include the siRNAdb database at the Stockholm Bioinformatics Centre, the MIT/ICBP siRNA Database, the RNAi Consortium shRNA Library at the Broad Institute, and the Probe database at NCBI. For example, there are 30,852 siRNA species in the NCBI Probe database. The skilled artisan will realize that for any gene of interest, either a siRNA species has already been designed, or one may readily be designed using publicly available software tools. Any such siRNA species may be delivered using the subject DNL complexes.

Exemplary siRNA species known in the art are listed in Table 5. Although siRNA is delivered as a double-stranded molecule, for simplicity only the sense strand sequences are shown in Table 5.

TABLE 5 Exemplary siRNA Sequences Target Sequence SEQ ID NO VEGF R2 AATGCGGCGGTGGTGAC SEQ ID NO: 97 AGTA VEGF R2 AAGCTCAGCACACAGAA SEQ ID NO: 98 AGAC CXCR4 UAAAAUCUUCCUGCCCA SEQ ID NO: 99 CCdTdT CXCR4 GGAAGCUGUUGGCUGAA SEQ ID NO: 100 AAdTdT PPARC1 AAGACCAGCCUCUUUGC SEQ ID NO: 101 CCAG Dynamin 2 GGACCAGGCAGAAAACG SEQ ID NO: 102 AG Catenin CUAUCAGGAUGACGCGG SEQ ID NO: 103 E1A binding UGACACAGGCAGGCUUG SEQ ID NO: 104 protein ACUU Plasminogen GGTGAAGAAGGGCGTCC SEQ ID NO: 105 activator AA K-ras GATCCGTTGGAGCTGTT SEQ ID NO: 106 GGCGTAGTTCAAGAGAC TCGCCAACAGCTCCAAC TTTTGGAAA Sortilin 1 AGGTGGTGTTAACAGCA SEQ ID NO: 107 GAG Apolipoprotein E AAGGTGGAGCAAGCGGT SEQ ID NO: 108 GGAG Apolipoprotein E AAGGAGTTGAAGGCCGA SEQ ID NO: 109 CAAA Bcl-X UAUGGAGCUGCAGAGGA SEQ ID NO: 110 UGdTdT Raf-1 TTTGAATATCTGTGCTG SEQ ID NO: 111 AGAACACAGTTCTCAGC ACAGATATTCTTTTT Heat shock AATGAGAAAAGCAAAAG SEQ ID NO: 112 transcription GTGCCCTGTCTC factor 2 IGFBP3 AAUCAUCAUCAAGAAAG SEQ ID NO: 113 GGCA Thioredoxin AUGACUGUCAGGAUGUU SEQ ID NO: 114 GCdTdT CD44 GAACGAAUCCUGAAGAC SEQ ID NO: 115 AUCU MMP14 AAGCCTGGCTACAGCAA SEQ ID NO: 116 TATGCCTGTCTC MAPKAPK2 UGACCAUCACCGAGUUU SEQ ID NO: 117 AUdTdT FGFR1 AAGTCGGACGCAACAGA SEQ ID NO: 118 GAAA ERBB2 CUACCUUUCUACGGACG SEQ ID NO: 119 UGdTdT BCL2L1 CTGCCTAAGGCGGATTT SEQ ID NO: 120 GAAT ABL1 TTAUUCCUUCUUCGGGA SEQ ID NO: 121 AGUC CEACAM1 AACCTTCTGGAACCCGC SEQ ID NO: 122 CCAC CD9 GAGCATCTTCGAGCAAG SEQ ID NO: 123 AA CD151 CATGTGGCACCGTTTGC SEQ ID NO: 124 CT Caspase 8 AACTACCAGAAAGGTAT SEQ ID NO: 125 ACCT BRCA1 UCACAGUGUCCUUUAUG SEQ ID NO: 126 UAdTdT p53 GCAUGAACCGGAGGCCC SEQ ID NO: 127 AUTT CEACAM6 CCGGACAGTTCCATGTA SEQ ID NO: 128 TA

The skilled artisan will realize that Table 5 represents a very small sampling of the total number of siRNA species known in the art, and that any such known siRNA may be utilized in the claimed methods and compositions.

Immunotoxins Comprising Ranpirnase (Rap)

Ribonucleases, in particular, Rap (Lee, Exp Opin Biol Ther 2008; 8:813-27) and its more basic variant, amphinase (Ardelt et al., Curr Pharm Biotechnol 2008:9:215-25), are potential anti-tumor agents (Lee and Raines, Biodrugs 2008; 22:53-8). Rap is a single-chain ribonuclease of 104 amino acids originally isolated from the oocytes of Rana pipiens. Rap exhibits cytostatic and cytotoxic effects on a variety of tumor cell lines in vitro, as well as antitumor activity in vivo. The amphibian ribonuclease enters cells via receptor-mediated endocytosis and once internalized into the cytosol, selectively degrades tRNA, resulting in inhibition of protein synthesis and induction of apoptosis.

Rap has completed a randomized Phase IIIb clinical trial, which compared the effectiveness of Rap plus doxorubicin with that of doxorubicin alone in patients with unresectable malignant mesothelioma, with the interim analysis showing that the MST for the combination was 12 months, while that of the monotherapy was 10 months (Mutti and Gaudino, Oncol Rev 2008; 2:61-5). Rap can be administered repeatedly to patients without an untoward immune response, with reversible renal toxicity reported to be dose-limiting (Mikulski et al., J Clin Oncol 2002; 20:274-81; Int J Oncol 1993; 3:57-64).

Conjugation or fusion of Rap to a tumor-targeting antibody or antibody fragment is a promising approach to enhance its potency, as first demonstrated for LL2-onconase (Newton et al., Blood 2001; 97:528-35), a chemical conjugate comprising Rap and a murine anti-CD22 monoclonal antibody (MAb), and subsequently for 2L-Rap-hLL1-γ4P, a fusion protein comprising Rap and a humanized anti-CD74 MAb (Stein et al., Blood 2004; 104:3705-11).

The method used to generate 2L-Rap-hLL1-γ4P allowed us to develop a series of structurally similar immunotoxins, referred to in general as 2L-Rap-X, all of which consist of two Rap molecules, each connected via a flexible linker to the N-terminus of one L chain of an antibody of interest (X). We have also generated another series of immunotoxins of the same design, referred to as 2LRap(Q)-X, by substituting Rap with its non-glycosylation form of Rap, designated as Rap(Q) to denote that the potential glycosylation site at Asn69 is changed to Gln (or Q, single letter code). For both series, we made the IgG as either IgG1(γ1) or IgG4(γ4), and to prevent the formation of IgG4 half molecules (Aalberse and Schuurman, Immunology 2002; 105:9-19), we converted the serine residue in the hinge region (S228) of IgG4 to proline (γ4P). A pyroglutamate residue at the N-terminus of Rap is required for the RNase to be fully functional (Liao et al., Nucleic Acids Res 2003; 31:5247-55).

The skilled artisan will recognize that the cytotoxic RNase moieties suitable for use in the present invention include polypeptides having a native ranpirnase structure and all enzymatically active variants thereof. These molecules advantageously have an N-terminal pyroglutamic acid resides that appears essential for RNase activity and are not substantially inhibited by mammalian RNase inhibitors. Nucleic acid that encodes a native cytotoxic RNase may be prepared by cloning and restriction of appropriate sequences, or using DNA amplification with polymerase chain reaction (PCR). The amino acid sequence of Rana Pipiens ranpirnase can be obtained from Ardelt et al., J. Biol. Chem., 256: 245 (1991), and cDNA sequences encoding native ranpirnase, or a conservatively modified variation thereof, can be gene-synthesized by methods similar to the en bloc V-gene assembly method used in hLL2 humanization. (Leung et al., Mol. Immunol., 32: 1413, 1995). Methods of making cytotoxic RNase variants are known in the art and are within the skill of the routineer.

As described in the Examples below, Rap conjugates of targeting antibodies may be made using the DNL technology. The DNL Rap-antibody constructs show potent cytotoxic activity that can be targeted to disease-associated cells.

Diagnostic Agents

In various embodiments, the DNL complexes may be conjugated to, or may bind a targetable construct comprising one or more diagnostic agents. Diagnostic agents are preferably selected from the group consisting of a radionuclide, a radiological contrast agent, a paramagnetic ion, a metal, a fluorescent label, a chemiluminescent label, an ultrasound contrast agent and a photoactive agent. Such diagnostic agents are well known and any such known diagnostic agent may be used. Non-limiting examples of diagnostic agents may include a radionuclide such as ¹⁸F, ⁵²Fe, ¹¹⁰In, ¹¹¹In, ¹⁷⁷Lu, ¹⁸F, ⁵²Fe, ⁶²Cu, ⁶⁴Cu, ⁶⁷Cu, ⁶⁷Ga, ⁶⁸Ga, ⁸⁶Y, ⁹⁰Y, ⁸⁹Zr, ^(94m)Tc, ⁹⁴Tc, ^(99m)Tc, ¹²⁰I, ¹²³I, ¹²⁴I, ¹²⁵I, ¹³¹I, ¹⁵⁴⁻¹⁵⁸Gd, ³²P, ¹¹C, ¹³N, ¹⁵O, ¹⁸⁶Re, ¹⁸⁸Re, ⁵¹Mn, ^(52m)Mn, ⁵⁵Co, ⁷²As, ⁷⁵Br, ⁷⁶Br, ^(82m)Rb, ⁸³Sr, or other gamma-, beta-, or positron-emitters.

Paramagnetic ions of use may include chromium (III), manganese (II), iron (III), iron (II), cobalt (II), nickel (II), copper (II), neodymium (III), samarium (III), ytterbium (III), gadolinium (III), vanadium (II), terbium (III), dysprosium (III), holmium (III) or erbium (III). Metal contrast agents may include lanthanum (III), gold (III), lead (II) or bismuth (III).

Ultrasound contrast agents may comprise liposomes, such as gas filled liposomes. Radiopaque diagnostic agents may be selected from compounds, barium compounds, gallium compounds, and thallium compounds. A wide variety of fluorescent labels are known in the art, including but not limited to fluorescein isothiocyanate, rhodamine, phycoerytherin, phycocyanin, allophycocyanin, o-phthaldehyde and fluorescamine. Chemiluminescent labels of use may include luminol, isoluminol, an aromatic acridinium ester, an imidazole, an acridinium salt or an oxalate ester.

Methods of Therapeutic Treatment

The claimed methods and compositions are of use for treating disease states, such as B-cell lymphomas or leukemias, autoimmune disease or immune system dysfunction (e.g., graft-versus-host disease). The methods may comprise administering a therapeutically effective amount of a therapeutic antibody or fragment thereof or an immunoconjugate, either alone or in conjunction with one or more other therapeutic agents, administered either concurrently or sequentially.

Multimodal therapies may include therapy with other antibodies, such as antibodies against CD4, CD5, CD8, CD14, CD15, CD19, CD20, CD21, CD22, CD23, CD25, CD33, CD37, CD38, CD40, CD40L, CD46, CD52, CD54, CD74, CD80, CD126, CD138, B7, HM1.24, HLA-DR, an angiogenesis factor, tenascin, VEGF, P1GF, ED-B fibronectin, an oncogene, an oncogene product, NCA 66a-d, necrosis antigens, Ii, IL-2, T101, TAC, IL-6, MUC-1, TRAIL-R1 (DR4) or TRAIL-R2 (DR5) in the form of naked antibodies, fusion proteins, or as immunoconjugates. Various antibodies of use are known to those of skill in the art. See, for example, Ghetie et al., Cancer Res. 48:2610 (1988); Hekman et al., Cancer Immunol. Immunother. 32:364 (1991); Longo, Curr. Opin. Oncol. 8:353 (1996), U.S. Pat. Nos. 5,798,554; 6,187,287; 6,306,393; 6,676,924; 7,109,304; 7,151,164; 7,230,084; 7,230,085; 7,238,785; 7,238,786; 7,282,567; 7,300,655; 7,312,318; 7,612,180; 7,501,498; the Examples section of each of which is incorporated herein by reference.

In another form of multimodal therapy, subjects may receive therapeutic DNL complexes in conjunction with standard chemotherapy. For example, “CVB” (1.5 g/m² cyclophosphamide, 200-400 mg/m² etoposide, and 150-200 mg/m² carmustine) is a regimen used to treat non-Hodgkin's lymphoma. Patti et al., Eur. J. Haematol. 51: 18 (1993). Other suitable combination chemotherapeutic regimens are well-known to those of skill in the art. See, for example, Freedman et al., “Non-Hodgkin's Lymphomas,” in CANCER MEDICINE, VOLUME 2, 3rd Edition, Holland et al. (eds.), pages 2028-2068 (Lea & Febiger 1993). As an illustration, first generation chemotherapeutic regimens for treatment of intermediate-grade non-Hodgkin's lymphoma (NHL) include C-MOPP (cyclophosphamide, vincristine, procarbazine and prednisone) and CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone). A useful second generation chemotherapeutic regimen is m-BACOD (methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, dexamethasone and leucovorin), while a suitable third generation regimen is MACOP-B (methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin and leucovorin). Additional useful drugs include phenyl butyrate, bendamustine, and bryostatin-1.

Therapeutic antibody complexes, such as DNL complexes, can be formulated according to known methods to prepare pharmaceutically useful compositions, whereby the therapeutic antibody complex is combined in a mixture with a pharmaceutically suitable excipient. Sterile phosphate-buffered saline is one example of a pharmaceutically suitable excipient. Other suitable excipients are well-known to those in the art. See, for example, Ansel et al., PHARMACEUTICAL DOSAGE FORMS AND DRUG DELIVERY SYSTEMS, 5th Edition (Lea & Febiger 1990), and Gennaro (ed.), REMINGTON'S PHARMACEUTICAL SCIENCES, 18th Edition (Mack Publishing Company 1990), and revised editions thereof.

The therapeutic antibody complex can be formulated for intravenous administration via, for example, bolus injection or continuous infusion. Preferably, the therapeutic antibody complex is infused over a period of less than about 4 hours, and more preferably, over a period of less than about 3 hours. For example, the first 25-50 mg could be infused within 30 minutes, preferably even 15 min, and the remainder infused over the next 2-3 hrs. Formulations for injection can be presented in unit dosage form, e.g., in ampoules or in multi-dose containers, with an added preservative. The compositions can take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and can contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient can be in powder form for constitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use.

The therapeutic antibody complex may also be administered to a mammal subcutaneously or even by other parenteral routes. Moreover, the administration may be by continuous infusion or by single or multiple boluses. Preferably, the therapeutic antibody complex is infused over a period of less than about 4 hours, and more preferably, over a period of less than about 3 hours.

More generally, the dosage of an administered therapeutic antibody complex for humans will vary depending upon such factors as the patient's age, weight, height, sex, general medical condition and previous medical history. It may be desirable to provide the recipient with a dosage of therapeutic antibody complex that is in the range of from about 1 mg/kg to 25 mg/kg as a single intravenous infusion, although a lower or higher dosage also may be administered as circumstances dictate. A dosage of 1-20 mg/kg for a 70 kg patient, for example, is 70-1,400 mg, or 41-824 mg/m² for a 1.7-m patient. The dosage may be repeated as needed, for example, once per week for 4-10 weeks, once per week for 8 weeks, or once per week for 4 weeks. It may also be given less frequently, such as every other week for several months, or monthly or quarterly for many months, as needed in a maintenance therapy.

Alternatively, a therapeutic antibody complex may be administered as one dosage every 2 or 3 weeks, repeated for a total of at least 3 dosages. Or, the therapeutic antibody complex may be administered twice per week for 4-6 weeks. If the dosage is lowered to approximately 200-300 mg/m² (340 mg per dosage for a 1.7-m patient, or 4.9 mg/kg for a 70 kg patient), it may be administered once or even twice weekly for 4 to 10 weeks. Alternatively, the dosage schedule may be decreased, namely every 2 or 3 weeks for 2-3 months. It has been determined, however, that even higher doses, such as 20 mg/kg once weekly or once every 2-3 weeks can be administered by slow i.v. infusion, for repeated dosing cycles. The dosing schedule can optionally be repeated at other intervals and dosage may be given through various parenteral routes, with appropriate adjustment of the dose and schedule.

Additional pharmaceutical methods may be employed to control the duration of action of the therapeutic immunoconjugate or naked antibody. Control release preparations can be prepared through the use of polymers to complex or adsorb the DNL complex. For example, biocompatible polymers include matrices of poly(ethylene-co-vinyl acetate) and matrices of a polyanhydride copolymer of a stearic acid dimer and sebacic acid. Sherwood et al., Bio/Technology 10: 1446 (1992). The rate of release of a DNL complex from such a matrix depends upon the molecular weight of the DNL complex, the amount of DNL complex within the matrix, and the size of dispersed particles. Saltzman et al., Biophys. J. 55: 163 (1989); Sherwood et al., supra. Other solid dosage forms are described in Ansel et al., PHARMACEUTICAL DOSAGE FORMS AND DRUG DELIVERY SYSTEMS, 5th Edition (Lea & Febiger 1990), and Gennaro (ed.), REMINGTON'S PHARMACEUTICAL SCIENCES, 18th Edition (Mack Publishing Company 1990), and revised editions thereof.

Cancer Therapy

In preferred embodiments, the DNL complexes are of use for therapy of cancer. Examples of cancers include, but are not limited to, carcinoma, lymphoma, glioblastoma, melanoma, sarcoma, and leukemia, myeloma, or lymphoid malignancies. More particular examples of such cancers are noted below and include: squamous cell cancer (e.g., epithelial squamous cell cancer), Ewing sarcoma, Wilms tumor, astrocytomas, lung cancer including small-cell lung cancer, non-small cell lung cancer, adenocarcinoma of the lung and squamous carcinoma of the lung, cancer of the peritoneum, hepatocellular cancer, gastric or stomach cancer including gastrointestinal cancer, pancreatic cancer, glioblastoma multiforme, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, hepatocellular carcinoma, neuroendocrine tumors, medullary thyroid cancer, differentiated thyroid carcinoma, breast cancer, ovarian cancer, colon cancer, rectal cancer, endometrial cancer or uterine carcinoma, salivary gland carcinoma, kidney or renal cancer, prostate cancer, vulvar cancer, anal carcinoma, penile carcinoma, as well as head-and-neck cancer. The term “cancer” includes primary malignant cells or tumors (e.g., those whose cells have not migrated to sites in the subject's body other than the site of the original malignancy or tumor) and secondary malignant cells or tumors (e.g., those arising from metastasis, the migration of malignant cells or tumor cells to secondary sites that are different from the site of the original tumor).

Other examples of cancers or malignancies include, but are not limited to: Acute Childhood Lymphoblastic Leukemia, Acute Lymphoblastic Leukemia, Acute Lymphocytic Leukemia, Acute Myeloid Leukemia, Adrenocortical Carcinoma, Adult (Primary) Hepatocellular Cancer, Adult (Primary) Liver Cancer, Adult Acute Lymphocytic Leukemia, Adult Acute Myeloid Leukemia, Adult Hodgkin's Lymphoma, Adult Lymphocytic Leukemia, Adult Non-Hodgkin's Lymphoma, Adult Primary Liver Cancer, Adult Soft Tissue Sarcoma, AIDS-Related Lymphoma, AIDS-Related Malignancies, Anal Cancer, Astrocytoma, Bile Duct Cancer, Bladder Cancer, Bone Cancer, Brain Stem Glioma, Brain Tumors, Breast Cancer, Cancer of the Renal Pelvis and Ureter, Central Nervous System (Primary) Lymphoma, Central Nervous System Lymphoma, Cerebellar Astrocytoma, Cerebral Astrocytoma, Cervical Cancer, Childhood (Primary) Hepatocellular Cancer, Childhood (Primary) Liver Cancer, Childhood Acute Lymphoblastic Leukemia, Childhood Acute Myeloid Leukemia, Childhood Brain Stem Glioma, Childhood Cerebellar Astrocytoma, Childhood Cerebral Astrocytoma, Childhood Extracranial Germ Cell Tumors, Childhood Hodgkin's Disease, Childhood Hodgkin's Lymphoma, Childhood Hypothalamic and Visual Pathway Glioma, Childhood Lymphoblastic Leukemia, Childhood Medulloblastoma, Childhood Non-Hodgkin's Lymphoma, Childhood Pineal and Supratentorial Primitive Neuroectodermal Tumors, Childhood Primary Liver Cancer, Childhood Rhabdomyosarcoma, Childhood Soft Tissue Sarcoma, Childhood Visual Pathway and Hypothalamic Glioma, Chronic Lymphocytic Leukemia, Chronic Myelogenous Leukemia, Colon Cancer, Cutaneous T-Cell Lymphoma, Endocrine Pancreas Islet Cell Carcinoma, Endometrial Cancer, Ependymoma, Epithelial Cancer, Esophageal Cancer, Ewing's Sarcoma and Related Tumors, Exocrine Pancreatic Cancer, Extracranial Germ Cell Tumor, Extragonadal Germ Cell Tumor, Extrahepatic Bile Duct Cancer, Eye Cancer, Female Breast Cancer, Gaucher's Disease, Gallbladder Cancer, Gastric Cancer, Gastrointestinal Carcinoid Tumor, Gastrointestinal Tumors, Germ Cell Tumors, Gestational Trophoblastic Tumor, Hairy Cell Leukemia, Head and Neck Cancer, Hepatocellular Cancer, Hodgkin's Lymphoma, Hypergammaglobulinemia, Hypopharyngeal Cancer, Intestinal Cancers, Intraocular Melanoma, Islet Cell Carcinoma, Islet Cell Pancreatic Cancer, Kaposi's Sarcoma, Kidney Cancer, Laryngeal Cancer, Lip and Oral Cavity Cancer, Liver Cancer, Lung Cancer, Lymphoproliferative Disorders, Macroglobulinemia, Male Breast Cancer, Malignant Mesothelioma, Malignant Thymoma, Medulloblastoma, Melanoma, Mesothelioma, Metastatic Occult Primary Squamous Neck Cancer, Metastatic Primary Squamous Neck Cancer, Metastatic Squamous Neck Cancer, Multiple Myeloma, Multiple Myeloma/Plasma Cell Neoplasm, Myelodysplastic Syndrome, Myelogenous Leukemia, Myeloid Leukemia, Myeloproliferative Disorders, Nasal Cavity and Paranasal Sinus Cancer, Nasopharyngeal Cancer, Neuroblastoma, Non-Hodgkin's Lymphoma, Nonmelanoma Skin Cancer, Non-Small Cell Lung Cancer, Occult Primary Metastatic Squamous Neck Cancer, Oropharyngeal Cancer, Osteo-/Malignant Fibrous Sarcoma, Osteosarcoma/Malignant Fibrous Histiocytoma, Osteosarcoma/Malignant Fibrous Histiocytoma of Bone, Ovarian Epithelial Cancer, Ovarian Germ Cell Tumor, Ovarian Low Malignant Potential Tumor, Pancreatic Cancer, Paraproteinemias, Polycythemia vera, Parathyroid Cancer, Penile Cancer, Pheochromocytoma, Pituitary Tumor, Primary Central Nervous System Lymphoma, Primary Liver Cancer, Prostate Cancer, Rectal Cancer, Renal Cell Cancer, Renal Pelvis and Ureter Cancer, Retinoblastoma, Rhabdomyosarcoma, Salivary Gland Cancer, Sarcoidosis Sarcomas, Sezary Syndrome, Skin Cancer, Small Cell Lung Cancer, Small Intestine Cancer, Soft Tissue Sarcoma, Squamous Neck Cancer, Stomach Cancer, Supratentorial Primitive Neuroectodermal and Pineal Tumors, T-Cell Lymphoma, Testicular Cancer, Thymoma, Thyroid Cancer, Transitional Cell Cancer of the Renal Pelvis and Ureter, Transitional Renal Pelvis and Ureter Cancer, Trophoblastic Tumors, Ureter and Renal Pelvis Cell Cancer, Urethral Cancer, Uterine Cancer, Uterine Sarcoma, Vaginal Cancer, Visual Pathway and Hypothalamic Glioma, Vulvar Cancer, Waldenstrom's Macroglobulinemia, Wilms' Tumor, and any other hyperproliferative disease, besides neoplasia, located in an organ system listed above.

The methods and compositions described and claimed herein may be used to treat malignant or premalignant conditions and to prevent progression to a neoplastic or malignant state, including but not limited to those disorders described above. Such uses are indicated in conditions known or suspected of preceding progression to neoplasia or cancer, in particular, where non-neoplastic cell growth consisting of hyperplasia, metaplasia, or most particularly, dysplasia has occurred (for review of such abnormal growth conditions, see Robbins and Angell, Basic Pathology, 2d Ed., W. B. Saunders Co., Philadelphia, pp. 68-79 (1976)).

Dysplasia is frequently a forerunner of cancer, and is found mainly in the epithelia. It is the most disorderly form of non-neoplastic cell growth, involving a loss in individual cell uniformity and in the architectural orientation of cells. Dysplasia characteristically occurs where there exists chronic irritation or inflammation. Dysplastic disorders which can be treated include, but are not limited to, anhidrotic ectodermal dysplasia, anterofacial dysplasia, asphyxiating thoracic dysplasia, atriodigital dysplasia, bronchopulmonary dysplasia, cerebral dysplasia, cervical dysplasia, chondroectodermal dysplasia, cleidocranial dysplasia, congenital ectodermal dysplasia, craniodiaphysial dysplasia, craniocarpotarsal dysplasia, craniometaphysial dysplasia, dentin dysplasia, diaphysial dysplasia, ectodermal dysplasia, enamel dysplasia, encephalo-ophthalmic dysplasia, dysplasia epiphysialis hemimelia, dysplasia epiphysialis multiplex, dysplasia epiphysialis punctata, epithelial dysplasia, faciodigitogenital dysplasia, familial fibrous dysplasia of jaws, familial white folded dysplasia, fibromuscular dysplasia, fibrous dysplasia of bone, florid osseous dysplasia, hereditary renal-retinal dysplasia, hidrotic ectodermal dysplasia, hypohidrotic ectodermal dysplasia, lymphopenic thymic dysplasia, mammary dysplasia, mandibulofacial dysplasia, metaphysial dysplasia, Mondini dysplasia, monostotic fibrous dysplasia, mucoepithelial dysplasia, multiple epiphysial dysplasia, oculoauriculovertebral dysplasia, oculodentodigital dysplasia, oculovertebral dysplasia, odontogenic dysplasia, opthalmomandibulomelic dysplasia, periapical cemental dysplasia, polyostotic fibrous dysplasia, pseudoachondroplastic spondyloepiphysial dysplasia, retinal dysplasia, septo-optic dysplasia, spondyloepiphysial dysplasia, and ventriculoradial dysplasia.

Additional pre-neoplastic disorders which can be treated include, but are not limited to, benign dysproliferative disorders (e.g., benign tumors, fibrocystic conditions, tissue hypertrophy, intestinal polyps or adenomas, and esophageal dysplasia), leukoplakia, keratoses, Bowen's disease, Farmer's Skin, solar cheilitis, and solar keratosis.

In preferred embodiments, the method of the invention is used to inhibit growth, progression, and/or metastasis of cancers, in particular those listed above.

Additional hyperproliferative diseases, disorders, and/or conditions include, but are not limited to, progression, and/or metastases of malignancies and related disorders such as leukemia (including acute leukemias (e.g., acute lymphocytic leukemia, acute myelocytic leukemia (including myeloblastic, promyelocytic, myelomonocytic, monocytic, and erythroleukemia)) and chronic leukemias (e.g., chronic myelocytic (granulocytic) leukemia and chronic lymphocytic leukemia)), polycythemia vera, lymphomas (e.g., Hodgkin's disease and non-Hodgkin's disease), multiple myeloma, Waldenstrom's macroglobulinemia, heavy chain disease, and solid tumors including, but not limited to, sarcomas and carcinomas such as fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer, breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilm's tumor, cervical cancer, testicular tumor, lung carcinoma, small cell lung carcinoma, bladder carcinoma, epithelial carcinoma, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, emangioblastoma, acoustic neuroma, oligodendroglioma, meningioma, melanoma, neuroblastoma, and retinoblastoma.

Therapy of Autoimmune Disease

Anti-CD20 and/or anti-CD22 DNL complexes can be used to treat immune dysregulation disease and related autoimmune diseases. Immune diseases may include acute idiopathic thrombocytopenic purpura, Addison's disease, adult respiratory distress syndrome (ARDS), agranulocytosis, allergic conditions, allergic encephalomyelitis, allergic neuritis, amyotrophic lateral sclerosis (ALS), ankylosing spondylitis, antigen-antibody complex mediated diseases, anti-glomerular basement membrane disease, anti-phospholipid antibody syndrome, aplastic anemia, arthritis, asthma, atherosclerosis, autoimmune disease of the testis and ovary, autoimmune endocrine diseases, autoimmune myocarditis, autoimmune neutropenia, autoimmune polyendocrinopathies, autoimmune polyglandular syndromes (or polyglandular endocrinopathy syndromes), autoimmune thrombocytopenia, Bechet disease, Berger's disease (IgA nephropathy), bronchiolitis obliterans (non-transplant), bullous pemphigoid, Castleman's syndrome, Celiac sprue (gluten enteropathy), central nervous system (CNS) inflammatory disorders, chronic active hepatitis, chronic idiopathic thrombocytopenic purpura dermatomyositis, colitis, conditions involving infiltration of T cells and chronic inflammatory responses, coronary artery disease, Crohn's disease, cryoglobulinemia, dermatitis, dermatomyositis, diabetes mellitus, diseases involving leukocyte diapedesis, eczema, encephalitis, erythema multiforme, erythema nodosum, Factor VIII deficiency, fibrosing alveolitis, giant cell arteritis, glomerulonephritis, Goodpasture's syndrome, graft versus host disease (GVHD), granulomatosis, Grave's disease, Guillain-Barre Syndrome, Hashimoto's thyroiditis, hemophilia A, Henoch-Schonlein purpura, idiopathic hypothyroidism, idiopathic thrombocytopenic purpura (ITP), IgA nephropathy, IgA nephropathy, IgM mediated neuropathy, immune complex nephritis, immune hemolytic anemia including autoimmune hemolytic anemia (AIHA), immune responses associated with acute and delayed hypersensitivity mediated by cytokines and T-lymphocytes, immune-mediated thrombocytopenias, juvenile onset diabetes, juvenile rheumatoid arthritis, Lambert-Eaton Myasthenic Syndrome, large vessel vasculitis, leukocyte adhesion deficiency, leukopenia, lupus nephritis, lymphoid interstitial pneumonitis (HIV), medium vessel vasculitis, membranous nephropathy, meningitis, multiple organ injury syndrome, multiple sclerosis, myasthenia gravis, osteoarthritis, pancytopenia, pemphigoid bullous, pemphigus vulgaris, pernicious anemia, polyarteritis nodosa, polychondritis, polyglandular syndromes, polymyalgia, polymyositis, post-streptococcal nephritis, primary biliary cirrhosis, primary hypothyroidism, psoriasis, psoriatic arthritis, pure red cell aplasia (PRCA), rapidly progressive glomerulonephritis, Reiter's disease, respiratory distress syndrome, responses associated with inflammatory bowel disease, Reynaud's syndrome, rheumatic fever, rheumatoid arthritis, sarcoidosis, scleroderma, Sjogren's syndrome, solid organ transplant rejection, Stevens-Johnson syndrome, stiff-man syndrome, subacute thyroiditis, Sydenham's chorea, systemic lupus erythematosus (SLE), systemic scleroderma and sclerosis, tabes dorsalis, Takayasu's arteritis, thromboangitis obliterans, thrombotic thrombocytopenic purpura (TTP), thyrotoxicosis, toxic epidermal necrolysis, tuberculosis, Type I diabetes, ulcerative colitis, uveitis, vasculitis (including ANCA) and Wegener's granulomatosis.

Kits

Various embodiments may concern kits containing DNL constructs and/or other components. Such components may include a targetable construct for use with such DNL complexes. In alternative embodiments it is contemplated that a targetable construct may be attached to one or more different therapeutic and/or diagnostic agents.

If the composition containing components for administration is not formulated for delivery via the alimentary canal, such as by oral delivery, a device capable of delivering the kit components through some other route may be included. One type of device, for applications such as parenteral delivery, is a syringe that is used to inject the composition into the body of a subject. Inhalation devices may also be used for certain applications.

The kit components may be packaged together or separated into two or more containers. In some embodiments, the containers may be vials that contain sterile, lyophilized formulations of a composition that are suitable for reconstitution. A kit may also contain one or more buffers suitable for reconstitution and/or dilution of other reagents. Other containers that may be used include, but are not limited to, a pouch, tray, box, tube, or the like. Kit components may be packaged and maintained sterilely within the containers. Another component that can be included is instructions to a person using a kit for its use.

EXAMPLES

Various embodiments of the present invention are illustrated by the following examples, without limiting the scope thereof.

Example 1. Preparation of Dock-and-Lock (DNL) Constructs

DDD and AD Fusion Proteins

The DNL technique can be used to make dimers, trimers, tetramers, hexamers, etc. comprising virtually any antibody, antibody fragment, immunomodulator, cytokine, PEG moiety, toxin, antigen or xenoantigen or other effector moiety. For certain preferred embodiments, antibodies and cytokines may be produced as fusion proteins comprising either a dimerization and docking domain (DDD) or anchoring domain (AD) sequence. Although in preferred embodiments the DDD and AD moieties may be joined to antibodies, antibody fragments, cytokines, toxins or other effector moieties as fusion proteins, the skilled artisan will realize that other methods of conjugation exist, such as chemical cross-linking, click chemistry reaction, etc.

The technique is not limiting and any protein or peptide of use may be produced as an AD or DDD fusion protein for incorporation into a DNL construct. Where chemical cross-linking is utilized, the AD and DDD conjugates may comprise any molecule that may be cross-linked to an AD or DDD sequence using any cross-linking technique known in the art. In certain exemplary embodiments, a dendrimer or other polymeric moiety such as polyethyleneimine or polyethylene glycol (PEG), may be incorporated into a DNL construct, as described in further detail below.

Expression Vectors

The plasmid vector pdHL2 has been used to produce a number of antibodies and antibody-based constructs. See Gillies et al., J Immunol Methods (1989), 125:191-202; Losman et al., Cancer (Phila) (1997), 80:2660-6. The di-cistronic mammalian expression vector directs the synthesis of the heavy and light chains of IgG. The vector sequences are mostly identical for many different IgG-pdHL2 constructs, with the only differences existing in the variable domain (V_(H) and V_(L)) sequences. Using molecular biology tools known to those skilled in the art, these IgG expression vectors can be converted into Fab-DDD or Fab-AD expression vectors.

To generate Fab-DDD expression vectors, the coding sequences for the hinge, CH2 and CH3 domains of the heavy chain were replaced with a sequence encoding the first 4 residues of the hinge, a 14 residue Gly-Ser linker and a DDD moiety, such as the first 44 residues of human RIIα (referred to as DDD1, SEQ ID NO:13). To generate Fab-AD expression vectors, the sequences for the hinge, CH2 and CH3 domains of IgG were replaced with a sequence encoding the first 4 residues of the hinge, a 15 residue Gly-Ser linker and an AD moiety, such as a 17 residue synthetic AD called AKAP-IS (referred to as AD1, SEQ ID NO:15), which was generated using bioinformatics and peptide array technology and shown to bind RIIα dimers with a very high affinity (0.4 nM). See Alto, et al. Proc. Natl. Acad. Sci., U.S.A (2003), 100:4445-50.

Two shuttle vectors were designed to facilitate the conversion of IgG-pdHL2 vectors to either Fab-DDD1 or Fab-AD1 expression vectors, as described below.

Preparation of CH1

The CH1 domain was amplified by PCR using the pdHL2 plasmid vector as a template. The left PCR primer consisted of the upstream (5′) end of the CH1 domain and a SacII restriction endonuclease site, which is 5′ of the CH1 coding sequence. The right primer consisted of the sequence coding for the first 4 residues of the hinge (PKSC, SEQ ID NO:129) followed by four glycines and a serine, with the final two codons (GS) comprising a Bam HI restriction site. The 410 bp PCR amplimer was cloned into the PGEMT® PCR cloning vector (PROMEGA®, Inc.) and clones were screened for inserts in the T7 (5′) orientation.

A duplex oligonucleotide was synthesized to code for the amino acid sequence of DDD1 preceded by 11 residues of the linker peptide, with the first two codons comprising a BamHI restriction site. A stop codon and an EagI restriction site are appended to the 3′ end. The encoded polypeptide sequence is shown below.

(SEQ ID NO: 130) GSGGGGSGGGGSHIQIPPGLTELLQGYTVEVLRQQPPDLVE  FAVEYFTRLREARA

Two oligonucleotides, designated RIIA1-44 top and RIIA1-44 bottom, which overlap by 30 base pairs on their 3′ ends, were synthesized and combined to comprise the central 154 base pairs of the 174 bp DDD1 sequence. The oligonucleotides were annealed and subjected to a primer extension reaction with Taq polymerase. Following primer extension, the duplex was amplified by PCR. The amplimer was cloned into PGEMT® and screened for inserts in the T7 (5′) orientation.

A duplex oligonucleotide was synthesized to code for the amino acid sequence of AD1 preceded by 11 residues of the linker peptide with the first two codons comprising a BamHI restriction site. A stop codon and an EagI restriction site are appended to the 3′ end. The encoded polypeptide sequence is shown below.

(SEQ ID NO: 131) GSGGGGSGGGGSQIEYLAKQIVDNAIQQA 

Two complimentary overlapping oligonucleotides encoding the above peptide sequence, designated AKAP-IS Top and AKAP-IS Bottom, were synthesized and annealed. The duplex was amplified by PCR. The amplimer was cloned into the PGEMT® vector and screened for inserts in the T7 (5′) orientation.

Ligating DDD1 with CH1

A 190 bp fragment encoding the DDD1 sequence was excised from PGEMT® with BamHI and NotI restriction enzymes and then ligated into the same sites in CH1-PGEMT® to generate the shuttle vector CH1-DDD1-PGEMT®.

Ligating AD1 with CH1

A 110 bp fragment containing the AD1 sequence was excised from PGEMT® with BamHI and NotI and then ligated into the same sites in CH₁—PGEMT® to generate the shuttle vector CH1-AD1-PGEMT®.

Cloning CH1-DDD1 or CH1-AD1 into pdHL2-Based Vectors

With this modular design either CH1-DDD1 or CH1-AD1 can be incorporated into any IgG construct in the pdHL2 vector. The entire heavy chain constant domain is replaced with one of the above constructs by removing the SacII/EagI restriction fragment (CH1-CH3) from pdHL2 and replacing it with the SacII/EagI fragment of CH1-DDD1 or CH1-AD1, which is excised from the respective PGEMT® shuttle vector.

Construction of h679-Fd-AD1-pdHL2

h679-Fd-AD1-pdHL2 is an expression vector for production of h679 Fab with AD1 coupled to the carboxyl terminal end of the CH1 domain of the Fd via a flexible Gly/Ser peptide spacer composed of 14 amino acid residues. A pdHL2-based vector containing the variable domains of h679 was converted to h679-Fd-AD1-pdHL2 by replacement of the SacII/EagI fragment with the CH1-AD1 fragment, which was excised from the CH1-AD1-SV3 shuttle vector with SacII and EagI.

Production and Purification of h679-Fab-AD1

The h679-Fd-AD1-pdHL2 vector was linearized by digestion with Sal I restriction endonuclease and transfected into Sp/EEE myeloma cells by electroporation. The di-cistronic expression vector directs the synthesis and secretion of both h679 kappa light chain and h679 Fd-AD1, which combine to form h679 Fab-AD1. Following electroporation, the cells were plated in 96-well tissue culture plates and transfectant clones were selected with 0.05 μM methotrexate (MTX). Clones were screened for protein expression by ELISA using microtiter plates coated with a BSA-IMP260 (HSG) conjugate and detection with HRP-conjugated goat anti-human Fab. BIAcore analysis using an HSG (IMP239) sensorchip was used to determine the productivity by measuring the initial slope obtained from injection of diluted media samples. The highest producing clone had an initial productivity of approximately 30 mg/L. A total of 230 mg of h679-Fab-AD1 was purified from 4.5 liters of roller bottle culture by single-step IMP291 affinity chromatography. Culture media was concentrated approximately 10-fold by ultrafiltration before loading onto an IMP291-affigel column. The column was washed to baseline with PBS and h679-Fab-AD1 was eluted with 1M imidazole, 1 mM EDTA, 0.1M NaAc, pH 4.5. SE-HPLC analysis of the eluate shows a single sharp peak with a retention time consistent with a 50 kDa protein (not shown). Only two bands, which represent the polypeptide constituents of h679-AD1, were evident by reducing SDS-PAGE analysis (not shown).

Construction of C-DDD1-Fd-hMN-14-pdHL2

C-DDD1-Fd-hMN-14-pdHL2 is an expression vector for production of a stable dimer that comprises two copies of a fusion protein C-DDD1-Fab-hMN-14, in which DDD1 is linked to hMN-14 Fab at the carboxyl terminus of CH1 via a flexible peptide spacer. The plasmid vector hMN-14(I)-pdHL2, which has been used to produce hMN-14 IgG, was converted to C-DDD1-Fd-hMN-14-pdHL2 by digestion with SacII and EagI restriction endonucleases to remove the CH1-CH3 domains and insertion of the CH1-DDD1 fragment, which was excised from the CH1-DDD1-SV3 shuttle vector with SacII and EagI.

The same technique has been utilized to produce plasmids for Fab expression of a wide variety of known antibodies, such as hLL1, hLL2, hPAM4, hR1, hRS7, hMN-14, hMN-15, hA19, hA20 and many others. Generally, the antibody variable region coding sequences were present in a pdHL2 expression vector and the expression vector was converted for production of an AD- or DDD-fusion protein as described above. The AD- and DDD-fusion proteins comprising a Fab fragment of any of such antibodies may be combined, in an approximate ratio of two DDD-fusion proteins per one AD-fusion protein, to generate a trimeric DNL construct comprising two Fab fragments of a first antibody and one Fab fragment of a second antibody.

Construction of N-DDD1-Fd-hMN-14-pdHL2

N-DDD1-Fd-hMN-14-pdHL2 is an expression vector for production of a stable dimer that comprises two copies of a fusion protein N-DDD1-Fab-hMN-14, in which DDD1 is linked to hMN-14 Fab at the amino terminus of V_(H) via a flexible peptide spacer. The expression vector was engineered as follows. The DDD1 domain was amplified by PCR.

As a result of the PCR, an NcoI restriction site and the coding sequence for part of the linker containing a BamHI restriction were appended to the 5′ and 3′ ends, respectively. The 170 bp PCR amplimer was cloned into the PGEMT® vector and clones were screened for inserts in the T7 (5′) orientation. The 194 bp insert was excised from the PGEMT® vector with NcoI and SalI restriction enzymes and cloned into the SV3 shuttle vector, which was prepared by digestion with those same enzymes, to generate the intermediate vector DDD 1-SV3.

The hMN-14 Fd sequence was amplified by PCR. As a result of the PCR, a BamHI restriction site and the coding sequence for part of the linker were appended to the 5′ end of the amplimer. A stop codon and EagI restriction site was appended to the 3′ end. The 1043 bp amplimer was cloned into pGemT. The hMN-14-Fd insert was excised from PGEMT® with BamHI and EagI restriction enzymes and then ligated with DDD 1-SV3 vector, which was prepared by digestion with those same enzymes, to generate the construct N-DDD1-hMN-14Fd-SV3.

The N-DDD1-hMN-14 Fd sequence was excised with XhoI and EagI restriction enzymes and the 1.28 kb insert fragment was ligated with a vector fragment that was prepared by digestion of C-hMN-14-pdHL2 with those same enzymes. The final expression vector was N-DDD1-Fd-hMN-14-pDHL2. The N-linked Fab fragment exhibited similar DNL complex formation and antigen binding characteristics as the C-linked Fab fragment (not shown).

Production and Purification of N-DDD1-Fab-hMN-14 and C-DDD1-Fab-hMN-14

The C-DDD1-Fd-hMN-14-pdHL2 and N-DDD1-Fd-hMN-14-pdHL2 vectors were transfected into Sp2/0-derived myeloma cells by electroporation. C-DDD1-Fd-hMN-14-pdHL2 is a di-cistronic expression vector, which directs the synthesis and secretion of both hMN-14 kappa light chain and hMN-14 Fd-DDD1, which combine to form C-DDD1-hMN-14 Fab. N-DDD1-hMN-14-pdHL2 is a di-cistronic expression vector, which directs the synthesis and secretion of both hMN-14 kappa light chain and N-DDD1-Fd-hMN-14, which combine to form N-DDD1-Fab-hMN-14. Each fusion protein forms a stable homodimer via the interaction of the DDD 1 domain.

Following electroporation, the cells were plated in 96-well tissue culture plates and transfectant clones were selected with 0.05 μM methotrexate (MTX). Clones were screened for protein expression by ELISA using microtiter plates coated with WI2 (a rat anti-id monoclonal antibody to hMN-14) and detection with HRP-conjugated goat anti-human Fab. The initial productivity of the highest producing C-DDD1-Fab-hMN14 Fab and N-DDD1-Fab-hMN14 Fab clones was 60 mg/L and 6 mg/L, respectively.

Affinity Purification of N-DDD1-hMN-14 and C-DDD1-hMN-14 with AD1-Affigel

The DDD/AD interaction was utilized to affinity purify DDD1-containing constructs. AD 1-C is a peptide that was made synthetically consisting of the AD1 sequence and a carboxyl terminal cysteine residue, which was used to couple the peptide to Affigel following reaction of the sulfhydryl group with chloroacetic anhydride. DDD-containing dimer structures specifically bind to the AD1-C-Affigel resin at neutral pH and can be eluted at low pH (e.g., pH 2.5).

A total of 81 mg of C-DDD1-Fab-hMN-14 was purified from 1.2 liters of roller bottle culture by single-step AD 1-C affinity chromatography. Culture media was concentrated approximately 10-fold by ultrafiltration before loading onto an AD1-C-affigel column. The column was washed to baseline with PBS and C-DDD1-Fab-hMN-14 was eluted with 0.1M Glycine, pH 2.5. SE-HPLC analysis of the eluate showed a single protein peak with a retention time consistent with a 107 kDa protein (not shown). The purify was also confirmed by reducing SDS-PAGE, showing only two bands of molecular size expected for the two polypeptide constituents of C-DDD1-Fab-hMN-14 (not shown).

A total of 10 mg of N-DDD1-hMN-14 was purified from 1.2 liters of roller bottle culture by single-step AD1-C affinity chromatography as described above. SE-HPLC analysis of the eluate showed a single protein peak with a retention time similar to C-DDD1-Fab-hMN-14 and consistent with a 107 kDa protein (not shown). Reducing SDS-PAGE showed only two bands attributed to the polypeptide constituents of N-DDD1-Fab-hMN-14 (not shown).

The binding activity of C-DDD1-Fab-hMN-14 was determined by SE-HPLC analysis of samples in which the test article was mixed with various amounts of WI2. A sample prepared by mixing WI2 Fab and C-DDD1-Fab-hMN-14 at a molar ratio of 0.75:1 showed three peaks, which were attributed to unbound C-DDD1-Fab-hMN14 (8.71 min), C-DDD1-Fab-hMN-14 bound to one WI2 Fab (7.95 min), and C-DDD1-Fab-hMN14 bound to two WI2 Fabs (7.37 min) (not shown). When a sample containing WI2 Fab and C-DDD1-Fab-hMN-14 at a molar ratio of 4 was analyzed, only a single peak at 7.36 minutes was observed (not shown). These results demonstrated that hMN14-Fab-DDD1 is dimeric and has two active binding sites. Very similar results were obtained when this experiment was repeated with N-DDD1-Fab-hMN-14.

A competitive ELISA demonstrated that both C-DDD1-Fab-hMN-14 and N-DDD1-Fab-hMN-14 bind to CEA with an avidity similar to hMN-14 IgG, and significantly stronger than monovalent hMN-14 Fab (not shown). ELISA plates were coated with a fusion protein containing the epitope (A3B3) of CEA for which hMN-14 is specific.

C-DDD2-Fd-hMN-14-pdHL2

C-DDD2-Fd-hMN-14-pdHL2 is an expression vector for production of C-DDD2-Fab-hMN-14, which possesses a dimerization and docking domain sequence of DDD2 (SEQ ID NO:14) appended to the carboxyl terminus of the Fd of hMN-14 via a 14 amino acid residue Gly/Ser peptide linker. The fusion protein secreted is composed of two identical copies of hMN-14 Fab held together by non-covalent interaction of the DDD2 domains.

The expression vector was engineered as follows. Two overlapping, complimentary oligonucleotides, which comprise the coding sequence for part of the linker peptide and residues 1-13 of DDD2, were made synthetically. The oligonucleotides were annealed and phosphorylated with T4 PNK, resulting in overhangs on the 5′ and 3′ ends that are compatible for ligation with DNA digested with the restriction endonucleases BamHI and PstI, respectively.

The duplex DNA was ligated with the shuttle vector CH1-DDD1-PGEMT®, which was prepared by digestion with BamHI and PstI, to generate the shuttle vector CH1-DDD2-PGEMT®. A 507 bp fragment was excised from CH1-DDD2-PGEMT® with SacII and EagI and ligated with the IgG expression vector hMN-14(I)-pdHL2, which was prepared by digestion with SacII and EagI. The final expression construct was designated C-DDD2-Fd-hMN-14-pdHL2. Similar techniques have been utilized to generated DDD2-fusion proteins of the Fab fragments of a number of different humanized antibodies.

N-DDD2-Fd-hMN-14-pdHL2

N-DDD2-hMN-14-pdHL2 is an expression vector for production of N-DDD2-Fab-hMN-14, which possesses a dimerization and docking domain sequence of DDD2 (SEQ ID NO:14) appended to the amino terminus of the Fd. The DDD2 is coupled to the V_(H) domain via a 15 amino acid residue Gly/Ser peptide linker. DDD2 has a cysteine residue preceding the dimerization and docking sequences, which are identical to those of DDD1. The fusion protein secreted is composed of two identical copies of hMN-14 Fab held together by non-covalent interaction of the DDD2 domains.

The expression vector was engineered as follows. Two overlapping, complimentary oligonucleotides (DDD2 Top and DDD2 Bottom), which comprise residues 1-13 of DDD2, were made synthetically. The oligonucleotides were annealed and phosphorylated with T4 polynucleotide kinase (PNK), resulting in overhangs on the 5′ and 3′ ends that are compatible for ligation with DNA digested with the restriction endonucleases NcoI and PstI, respectively.

The duplex DNA was ligated with a vector fragment, DDD1-hMN14 Fd-SV3 that was prepared by digestion with NcoI and PstI, to generate the intermediate construct DDD2-hMN14 Fd-SV3. A 1.28 kb insert fragment, which contained the coding sequence for DDD2-hMN14 Fd, was excised from the intermediate construct with XhoI and EagI restriction endonucleases and ligated with hMN14-pdHL2 vector DNA that was prepared by digestion with those same enzymes. The final expression vector is N-DDD2-Fd-hMN-14-pdHL2.

h679-Fd-AD2-pdHL2

h679-Fab-AD2, was designed to pair to C-DDD2-Fab-hMN-14. h679-Fd-AD2-pdHL2 is an expression vector for the production of h679-Fab-AD2, which possesses an anchoring domain sequence of AD2 (SEQ ID NO:16) appended to the carboxyl terminal end of the CH1 domain via a 14 amino acid residue Gly/Ser peptide linker. AD2 has one cysteine residue preceding and another one following the anchor domain sequence of AD 1.

The expression vector was engineered as follows. Two overlapping, complimentary oligonucleotides (AD2 Top and AD2 Bottom), which comprise the coding sequence for AD2 and part of the linker sequence, were made synthetically. The oligonucleotides were annealed and phosphorylated with T4 PNK, resulting in overhangs on the 5′ and 3′ ends that are compatible for ligation with DNA digested with the restriction endonucleases BamHI and SpeI, respectively.

The duplex DNA was ligated into the shuttle vector CH1-AD1-PGEMT®, which was prepared by digestion with BamHI and SpeI, to generate the shuttle vector CH1-AD2-PGEMT®. A 429 base pair fragment containing CH1 and AD2 coding sequences was excised from the shuttle vector with SacII and EagI restriction enzymes and ligated into h679-pdHL2 vector that prepared by digestion with those same enzymes. The final expression vector is h679-Fd-AD2-pdHL2.

Example 2. Generation of TF1 DNL Construct

A large scale preparation of a DNL construct, referred to as TF1, was carried out as follows. N-DDD2-Fab-hMN-14 (Protein L-purified) and h679-Fab-AD2 (IMP-291-purified) were first mixed in roughly stoichiometric concentrations in 1 mM EDTA, PBS, pH 7.4. Before the addition of TCEP, SE-HPLC did not show any evidence of a₂b formation (not shown). Instead there were peaks representing a₄ (7.97 min; 200 kDa), a₂ (8.91 min; 100 kDa) and B (10.01 min; 50 kDa). Addition of 5 mM TCEP rapidly resulted in the formation of the a₂b complex as demonstrated by a new peak at 8.43 min, consistent with a 150 kDa protein (not shown). Apparently there was excess B in this experiment as a peak attributed to h679-Fab-AD2 (9.72 min) was still evident yet no apparent peak corresponding to either a₂ or a₄ was observed. After reduction for one hour, the TCEP was removed by overnight dialysis against several changes of PBS. The resulting solution was brought to 10% DMSO and held overnight at room temperature.

When analyzed by SE-HPLC, the peak representing a₂b appeared to be sharper with a slight reduction of the retention time by 0.1 min to 8.31 min (not shown), which, based on our previous findings, indicates an increase in binding affinity. The complex was further purified by IMP-291 affinity chromatography to remove the kappa chain contaminants. As expected, the excess h679-AD2 was co-purified and later removed by preparative SE-HPLC (not shown).

TF1 is a highly stable complex. When TF1 was tested for binding to an HSG (IMP-239) sensorchip, there was no apparent decrease of the observed response at the end of sample injection. In contrast, when a solution containing an equimolar mixture of both C-DDD1-Fab-hMN-14 and h679-Fab-AD1 was tested under similar conditions, the observed increase in response units was accompanied by a detectable drop during and immediately after sample injection, indicating that the initially formed a₂b structure was unstable. Moreover, whereas subsequent injection of WI2 gave a substantial increase in response units for TF1, no increase was evident for the C-DDD1/AD1 mixture.

The additional increase of response units resulting from the binding of WI2 to TF1 immobilized on the sensorchip corresponds to two fully functional binding sites, each contributed by one subunit of N-DDD2-Fab-hMN-14. This was confirmed by the ability of TF1 to bind two Fab fragments of WI2 (not shown). When a mixture containing h679-AD2 and N-DDD1-hMN14, which had been reduced and oxidized exactly as TF1, was analyzed by BIAcore, there was little additional binding of WI2 (not shown), indicating that a disulfide-stabilized a₂b complex such as TF1 could only form through the interaction of DDD2 and AD2.

Two improvements to the process were implemented to reduce the time and efficiency of the process. First, a slight molar excess of N-DDD2-Fab-hMN-14 present as a mixture of a₄/a₂ structures was used to react with h679-Fab-AD2 so that no free h679-Fab-AD2 remained and any a₄/a₂ structures not tethered to h679-Fab-AD2, as well as light chains, would be removed by IMP-291 affinity chromatography. Second, hydrophobic interaction chromatography (HIC) has replaced dialysis or diafiltration as a means to remove TCEP following reduction, which would not only shorten the process time but also add a potential viral removing step. N-DDD2-Fab-hMN-14 and 679-Fab-AD2 were mixed and reduced with 5 mM TCEP for 1 hour at room temperature. The solution was brought to 0.75M ammonium sulfate and then loaded onto a Butyl FF HIC column. The column was washed with 0.75M ammonium sulfate, 5 mM EDTA, PBS to remove TCEP. The reduced proteins were eluted from the HIC column with PBS and brought to 10% DMSO. Following incubation at room temperature overnight, highly purified TF1 was isolated by IMP-291 affinity chromatography (not shown). No additional purification steps, such as gel filtration, were required.

Example 3. Generation of TF2 DNL Construct

A trimeric DNL construct designated TF2 was obtained by reacting C-DDD2-Fab-hMN-14 with h679-Fab-AD2. A pilot batch of TF2 was generated with >90% yield as follows. Protein L-purified C-DDD2-Fab-hMN-14 (200 mg) was mixed with h679-Fab-AD2 (60 mg) at a 1.4:1 molar ratio. The total protein concentration was 1.5 mg/ml in PBS containing 1 mM EDTA. Subsequent steps involved TCEP reduction, HIC chromatography, DMSO oxidation, and IMP 291 affinity chromatography. Before the addition of TCEP, SE-HPLC did not show any evidence of a₂b formation. Addition of 5 mM TCEP rapidly resulted in the formation of a₂b complex consistent with a 157 kDa protein expected for the binary structure. TF2 was purified to near homogeneity by IMP 291 affinity chromatography (not shown). IMP 291 is a synthetic peptide containing the HSG hapten to which the 679 Fab binds (Rossi et al., 2005, Clin Cancer Res 11:7122s-29s). SE-HPLC analysis of the IMP 291 unbound fraction demonstrated the removal of a₄, a₂ and free kappa chains from the product (not shown).

The functionality of TF2 was determined by BIACORE® assay. TF2, C-DDD1-hMN-14+h679-AD1 (used as a control sample of noncovalent a₂b complex), or C-DDD2-hMN-14+h679-AD2 (used as a control sample of unreduced a₂ and b components) were diluted to 1 μg/ml (total protein) and passed over a sensorchip immobilized with HSG. The response for TF2 was approximately two-fold that of the two control samples, indicating that only the h679-Fab-AD component in the control samples would bind to and remain on the sensorchip. Subsequent injections of WI2 IgG, an anti-idiotype antibody for hMN-14, demonstrated that only TF2 had a DDD-Fab-hMN-14 component that was tightly associated with h679-Fab-AD as indicated by an additional signal response. The additional increase of response units resulting from the binding of WI2 to TF2 immobilized on the sensorchip corresponded to two fully functional binding sites, each contributed by one subunit of C-DDD2-Fab-hMN-14. This was confirmed by the ability of TF2 to bind two Fab fragments of WI2 (not shown).

Example 4. Production of TF10 DNL Construct

A similar protocol was used to generate a trimeric TF10 DNL construct, comprising two copies of a C-DDD2-Fab-hPAM4 and one copy of C-AD2-Fab-679. The TF10 bispecific ([hPAM4]₂×h679) antibody was produced using the method disclosed for production of the (anti CEA)₂× anti HSG bsAb TF2, as described above. The TF10 construct bears two humanized PAM4 Fabs and one humanized 679 Fab.

The two fusion proteins (hPAM4-DDD2 and h679-AD2) were expressed independently in stably transfected myeloma cells. The tissue culture supernatant fluids were combined, resulting in a two-fold molar excess of hPAM4-DDD2. The reaction mixture was incubated at room temperature for 24 hours under mild reducing conditions using 1 mM reduced glutathione. Following reduction, the DNL reaction was completed by mild oxidation using 2 mM oxidized glutathione. TF10 was isolated by affinity chromatography using IMP291-affigel resin, which binds with high specificity to the h679 Fab.

Example 5. Serum Stability of TF1 and TF2

TF1 and TF2 were designed to be DNL complexes that could be used in vivo where extensive dilution in blood and tissues would occur. The stability of TF2 in human sera was assessed using BIACORE. TF2 was diluted to 0.1 mg/ml in fresh human serum, which was pooled from four donors, and incubated at 37° C. under 5% CO₂ for seven days. Daily samples were diluted 1:25 and then analyzed by BIACORE using an IMP239 HSG sensorchip. An injection of WI2 IgG was used to quantify the amount of intact and fully active TF2. Serum samples were compared to control samples that were diluted directly from the stock. TF2 was highly stable in serum, retaining 98% of its bispecific binding activity after 7 days (not shown). Similar results were obtained for TF1 in either human or mouse serum (not shown).

Example 6. Biodistribution of TF2 in Tumor-Bearing Mice

Biodistribution studies were performed for TF2 in female athymic nude mice bearing s.c. human colorectal adenocarcinoma xenografts (LS 174T). Cells were expanded in tissue culture until enough cells had been grown to inject 50 mice s.c. with 1×10⁷ cells per mouse. After one week, tumors were measured and mice assigned to groups of 5 mice per time-point. The mean tumor size at the start of this study was 0.141±0.044 cm³. All the mice were injected with 40 μg ¹²⁵I-TF2 (250 pmoles, 2 μCi). They were then sacrificed and necropsied at 0.5, 2, 4, 16, 24, 48, and 72 hrs post-injection. A total of 35 mice were used in this study. Tumor as well as various tissues were removed and placed in a gamma-counter to determine percent-injected dose per gram (% ID/g) in tissue at each time-point.

Radioiodination of ¹²⁵I-TF2 resulted in 2.7% unbound isotope with a specific activity of 1.48 mCi/mg. The labeled sample was then subjected to SE-HPLC alone and after mixing with a 20-fold molar excess of CEA. Approximately 83% of the TF2 eluted off with a retention time of 10.1 minutes (not shown). There was 9% aggregated material (RT=9.03 min) and 8% low molecular weight material (RT=14.37 min) in the labeled TF2 (not shown). When mixed with CEA, 95% of the labeled TF2 shifted to a high molecular weigh species (RT=7.25 min) (not shown). These results indicated that the labeled preparation was acceptable for administration to the tumor-bearing mice.

Peak tumor uptake occurred at 4 h post-injection (10.3.+−.2.1% ID/g). Between 16 and 24 h post-injection, the amount of TF2 in the tumor is not significantly different (5.3±1.1% ID/g and 5.37±0.7% ID/g), indicating that peptide could be administered anytime between these two time-points, depending on blood values, without impacting tumor targeting. Uptake and clearance of TF2 from normal tissues was very similar to what has been observed previously for TF1. Both TF1 and TF2 appeared to favor clearance through the RES system (spleen and liver).

Example 7. Production of AD- and DDD-linked Fab and IgG Fusion Proteins From Multiple Antibodies

Using the techniques described in the preceding Examples, the IgG and Fab fusion proteins shown in Table 6 were constructed and incorporated into DNL constructs. The fusion proteins retained the antigen-binding characteristics of the parent antibodies and the DNL constructs exhibited the antigen-binding activities of the incorporated antibodies or antibody fragments.

TABLE 6 Fusion proteins comprising IgG or Fab Fusion Protein Binding Specificity C-AD1-Fab-h679 HSG C-AD2-Fab-h679 HSG C-(AD)₂-Fab-h679 HSG C-AD2-Fab-h734 Indium-DTPA C-AD2-Fab-hA20 CD20 C-AD2-Fab-hA20L CD20 C-AD2-Fab-hL243 HLA-DR C-AD2-Fab-hLL2 CD22 N-AD2-Fab-hLL2 CD22 C-AD2-IgG-hMN-14 CEACAM5 C-AD2-IgG-hR1 IGF-1R C-AD2-IgG-hRS7 EGP-1 C-AD2-IgG-hPAM4 MUC C-AD2-IgG-hLL1 CD74 C-DDD1-Fab-hMN-14 CEACAM5 C-DDD2-Fab-hMN-14 CEACAM5 C-DDD2-Fab-h679 HSG C-DDD2-Fab-hA19 CD19 C-DDD2-Fab-hA20 CD20 C-DDD2-Fab-hAFP AFP C-DDD2-Fab-hL243 HLA-DR C-DDD2-Fab-hLL1 CD74 C-DDD2-Fab-hLL2 CD22 C-DDD2-Fab-hMN-3 CEACAM6 C-DDD2-Fab-hMN-15 CEACAM6 C-DDD2-Fab-hPAM4 MUC C-DDD2-Fab-hR1 IGF-1R C-DDD2-Fab-hRS7 EGP-1 N-DDD2-Fab-hMN-14 CEACAM5

Example 8. Antibody-Dendrimer DNL Complex for siRNA

Cationic polymers, such as polylysine, polyethylenimine, or polyamidoamine (PAMAM)-based dendrimers, form complexes with nucleic acids. However, their potential applications as non-viral vectors for delivering therapeutic genes or siRNAs remain a challenge. One approach to improve selectivity and potency of a dendrimeric nanoparticle may be achieved by conjugation with an antibody that internalizes upon binding to target cells.

We synthesized and characterized a novel immunoconjugate, designated E1-G5/2, which was made by the DNL method to comprise half of a generation 5 (G5) PAMAM dendrimer (G5/2) site-specifically linked to a stabilized dimer of Fab derived from hRS7, a humanized antibody that is rapidly internalized upon binding to the Trop-2 antigen expressed on various solid cancers.

Methods

E1-G5/2 was prepared by combining two self-assembling modules, AD2-G5/2 and hRS7-Fab-DDD2, under mild redox conditions, followed by purification on a Protein L column. To make AD2-G5/2, we derivatized the AD2 peptide with a maleimide group to react with the single thiol generated from reducing a G5 PAMAM with a cystamine core and used reversed-phase HPLC to isolate AD2-G5/2. We produced hRS7-Fab-DDD2 as a fusion protein in myeloma cells, as described in the Examples above.

The molecular size, purity and composition of E1-G5/2 were analyzed by size-exclusion HPLC, SDS-PAGE, and Western blotting. The biological functions of E1-G5/2 were assessed by binding to an anti-idiotype antibody against hRS7, a gel retardation assay, and a DNase protection assay.

Results

E1-G5/2 was shown by size-exclusion HPLC to consist of a major peak (>90%) flanked by several minor peaks (not shown). The three constituents of E1-G5/2 (Fd-DDD2, the light chain, and AD2-G5/2) were detected by reducing SDS-PAGE and confirmed by Western blotting (not shown). Anti-idiotype binding analysis revealed E1-G5/2 contained a population of antibody-dendrimer conjugates of different size, all of which were capable of recognizing the anti-idiotype antibody, thus suggesting structural variability in the size of the purchased G5 dendrimer (not shown). Gel retardation assays showed E1-G5/2 was able to maximally condense plasmid DNA at a charge ratio of 6:1 (+/−), with the resulting dendriplexes completely protecting the complexed DNA from degradation by DNase I (not shown).

Conclusion

The DNL technique can be used to build dendrimer-based nanoparticles that are targetable with antibodies. Such agents have improved properties as carriers of drugs, plasmids or siRNAs for applications in vitro and in vivo. In preferred embodiments, anti-B-cell antibodies, such as anti-CD20 and/or anti-CD22, may be utilized to deliver cytotoxic or cytostatic siRNA species to targeted B-cells for therapy of lymphoma, leukemia, autoimmune or other diseases and conditions.

Example 9. Maleimide AD2 Conjugate for DNL Dendrimers

The peptide IMP 498 up to and including the PEG moiety was synthesized on a Protein Technologies PS3 peptide synthesizer by the Fmoc method on Sieber Amide resin (0.1 mmol scale). The maleimide was added manually by mixing the β-maleimidopropionic acid NHS ester with diisopropylethylamine and DMF with the resin for 4 hr. The peptide was cleaved from the resin with 15 mL TFA, 0.5 mL H₂O, 0.5 mL triisopropylsilane, and 0.5 mL thioanisole for 3 hr at room temperature. The peptide was purified by reverse phase HPLC using H₂O/CH₃CN TFA buffers to obtain about 90 mg of purified product after lyophilization.

Synthesis of Reduced G5 Dendrimer (G5/2)

The G-5 dendrimer (10% in MeOH, Dendritic Nanotechnologies), 2.03 g, 7.03×10⁻⁶ mol was reduced with 0.1426 TCEP.HCl 1:1 MeOH/H₂O (˜4 mL) and stirred overnight at room temperature. The reaction mixture was purified by reverse phase HPLC on a C-18 column eluted with 0.1% TFA H₂O/CH₃CN buffers to obtain 0.0633 g of the desired product after lyophilization.

Synthesis of G5/2 Dendrimer-AD2 Conjugate

The G5/2 Dendrimer, 0.0469 g (3.35×10⁻⁶ mol) was mixed with 0.0124 g of IMP 498 (4.4×10⁻⁶ mol) and dissolved in 1:1 MeOH/1M NaHCO₃ and mixed for 19 hr at room temperature followed by treatment with 0.0751 g dithiothreitol and 0.0441 g TCEP.HCl. The solution was mixed overnight at room temperature and purified on a C4 reverse phase HPLC column using 0.1% TFA H₂O/CH₃CN buffers to obtain 0.0033 g of material containing the conjugated AD2 and dendrimer as judged by gel electrophoresis and Western blot.

Example 10. Targeted Delivery of siRNA Using Protamine Linked Antibodies

Summary

RNA interference (RNAi) has been shown to down-regulate the expression of various proteins such as HER2, VEGF, Raf-1, bcl-2, EGFR and numerous others in preclinical studies. Despite the potential of RNAi to silence specific genes, the full therapeutic potential of RNAi remains to be realized due to the lack of an effective delivery system to target cells in vivo.

To address this critical need, we developed novel DNL constructs having multiple copies of human protamine tethered to a tumor-targeting, internalizing hRS7 (anti-Trop-2) antibody for targeted delivery of siRNAs in vivo. A DDD2-L-thP1 module comprising truncated human protamine (thP1, residues 8 to 29 of human protamine 1) was produced, in which the sequences of DDD2 and thP1 were fused respectively to the N- and C-terminal ends of a humanized antibody light chain (not shown). The sequence of the truncated hP1 (thP1) is shown below. Reaction of DDD2-L-thP1 with the antibody hRS7-IgG-AD2 under mild redox conditions, as described in the Examples above, resulted in the formation of an E1-L-thP1 complex (not shown), comprising four copies of thP1 attached to the carboxyl termini of the hRS7 heavy chains.

tHP1 (SEQ ID NO: 133) RSQSRSRYYRQRQRSRRRRRRS 

The purity and molecular integrity of E1-L-thP1 following Protein A purification were determined by size-exclusion HPLC and SDS-PAGE (not shown). In addition, the ability of E1-L-thP1 to bind plasmid DNA or siRNA was demonstrated by the gel shift assay (not shown). E1-L-thP1 was effective at binding short double-stranded oligonucleotides (not shown) and in protecting bound DNA from digestion by nucleases added to the sample or present in serum (not shown).

The ability of the E1-L-thP1 construct to internalize siRNAs into Trop-2-expressing cancer cells was confirmed by fluorescence microscopy using FITC-conjugated siRNA and the human Calu-3 lung cancer cell line (not shown).

Methods

The DNL technique was employed to generate E1-L-thP1. The hRS7 IgG-AD module, constructed as described in the Examples above, was expressed in myeloma cells and purified from the culture supernatant using Protein A affinity chromatography. The DDD2-L-thP1 module was expressed as a fusion protein in myeloma cells and was purified by Protein L affinity chromatography. Since the CH3-AD2-IgG module possesses two AD2 peptides and each can bind to a DDD2 dimer, with each DDD2 monomer attached to a protamine moiety, the resulting E1-L-thP1 conjugate comprises four protamine groups. E1-L-thp1 was formed in nearly quantitative yield from the constituent modules and was purified to near homogeneity (not shown) with Protein A.

DDD2-L-thP1 was purified using Protein L affinity chromatography and assessed by size exclusion HPLC analysis and SDS-PAGE under reducing and nonreducing conditions (data not shown). A major peak was observed at 9.6 min (not shown). SDS-PAGE showed a major band between 30 and 40 kDa in reducing gel and a major band about 60 kDa (indicating a dimeric form of DDD2-L-thP1) in nonreducing gel (not shown). The results of Western blotting confirmed the presence of monomeric DDD2-L-tP1 and dimeric DDD2-L-tP1 on probing with anti-DDD antibodies (not shown).

To prepare the E1-L-thP1, hRS7-IgG-AD2 and DDD2-L-thP1 were combined in approximately equal amounts and reduced glutathione (final concentration 1 mM) was added. Following an overnight incubation at room temperature, oxidized glutathione was added (final concentration 2 mM) and the incubation continued for another 24 h. E1-L-thP1 was purified from the reaction mixture by Protein A column chromatography and eluted with 0.1M sodium citrate buffer (pH 3.5). The product peak (not shown) was neutralized, concentrated, dialyzed with PBS, filtered, and stored in PBS containing 5% glycerol at 2 to 8° C. The composition of E1-L-thP1 was confirmed by reducing SDS-PAGE (not shown), which showed the presence of all three constituents (AD2-appended heavy chain, DDD2-L-htP1, and light chain).

The ability of DDD2-L-thP1 and E1-L-thP1 to bind DNA was evaluated by gel shift assay. DDD2-L-thP1 retarded the mobility of 500 ng of a linear form of 3-kb DNA fragment in 1% agarose at a molar ratio of 6 or higher (not shown). E1-L-thP1 retarded the mobility of 250 ng of a linear 200-bp DNA duplex in 2% agarose at a molar ratio of 4 or higher (not shown), whereas no such effect was observed for hRS7-IgG-AD2 alone (not shown). The ability of E1-L-thP1 to protect bound DNA from degradation by exogenous DNase and serum nucleases was also demonstrated (not shown).

The ability of E1-L-thP1 to promote internalization of bound siRNA was examined in the Trop-2 expressing ME-180 cervical cell line (not shown). Internalization of the E1-L-thP1 complex was monitored using FITC conjugated goat anti-human antibodies. The cells alone showed no fluorescence (not shown). Addition of FITC-labeled siRNA alone resulted in minimal internalization of the siRNA (not shown). Internalization of E1-L-thP1 alone was observed in 60 minutes at 37° C. (not shown). E1-L-thP1 was able to effectively promote internalization of bound FITC-conjugated siRNA (not shown). E1-L-thP1 (10 μg) was mixed with FITC-siRNA (300 nM) and allowed to form E1-L-thP1-siRNA complexes which were then added to Trop-2-expressing Calu-3 cells. After incubation for 4 h at 37° C. the cells were checked for internalization of siRNA by fluorescence microscopy (not shown).

The ability of E1-L-thP1 to induce apoptosis by internalization of siRNA was examined. E1-L-thP1 (10 μg) was mixed with varying amounts of siRNA (AllStars Cell Death siRNA, Qiagen, Valencia, Calif.). The E1-L-thP1-siRNA complex was added to ME-180 cells. After 72 h of incubation, cells were trypsinized and annexin V staining was performed to evaluate apoptosis. The Cell Death siRNA alone or E1-L-thP1 alone had no effect on apoptosis (not shown). Addition of increasing amounts of E1-L-thP1-siRNA produced a dose-dependent increase in apoptosis (not shown). These results show that E1-L-thP1 could effectively deliver siRNA molecules into the cells and induce apoptosis of target cells.

Conclusions

The DNL technology provides a modular approach to efficiently tether multiple protamine molecules to the anti-Trop-2 hRS7 antibody resulting in the novel molecule E1-L-thP1. SDS-PAGE demonstrated the homogeneity and purity of E1-L-thP1. DNase protection and gel shift assays showed the DNA binding activity of E1-L-thP1. E1-L-thP1 internalized in the cells like the parental hRS7 antibody and was able to effectively internalize siRNA molecules into Trop-2-expressing cells, such as ME-180 and Calu-3.

The skilled artisan will realize that the DNL technique is not limited to any specific antibody or siRNA species. Rather, the same methods and compositions demonstrated herein can be used to make targeted delivery complexes comprising any antibody (e.g., anti-CD20 or anti-CD22), any siRNA carrier and any siRNA species. The use of a bivalent IgG in targeted delivery complexes would result in prolonged circulating half-life and higher binding avidity to target cells, resulting in increased uptake and improved efficacy.

Example 11. Ribonuclease Based DNL Immunotoxins Comprising Quadruple Ranpirnase (Rap) Conjugated to B-Cell Targeting Antibodies

We applied the DNL method to generate a novel class of immunotoxins, each of which comprises four copies of Rap site-specifically linked to a bivalent IgG. We combined a recombinant Rap-DDD module, produced in E. coli, with recombinant, humanized IgG-AD modules, which were produced in myeloma cells and targeted B-cell lymphomas and leukemias via binding to CD20 (hA20, veltuzumab), CD22 (hLL2, epratuzumab) or HLA-DR (hL243, IMMU-114), to generate 20-Rap, 22-Rap and C2-Rap, respectively. For each construct, a dimer of Rap was covalently tethered to the C-terminus of each heavy chain of the respective IgG. A control construct, 14-Rap, was made similarly, using labetuzumab (hMN-14), that binds to an antigen (CEACAM5) not expressed on B-cell lymphomas/leukemias.

Rap-DDD2 (SEQ ID NO: 134) pQDWLTFQKKHITNTRDVDCDNIMSTNLFHCKDKNTFIYSRPEPVKAIC KGIIASKNVLTTSEFYLSDCNVTSRPCKYKLKKSTNKFCVTCENQAPVH FVGVGSC GGGGSLE CGHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVE  YFTRLREARA VEHHHHHH

The deduced amino acid sequence of secreted Rap-DDD2 is shown above (SEQ ID NO:134). Rap, underlined; linker, italics; DDD2, bold; pQ, amino-terminal glutamine converted to pyroglutamate. Rap-DDD2 was produced in E. coli as inclusion bodies, which were purified by IMAC under denaturing conditions, refolded and then dialyzed into PBS before purification by Q-Sepharose anion exchange chromatography. SDS-PAGE under reducing conditions resolved a protein band with a Mr appropriate for Rap-DDD2 (18.6 kDa) (not shown). The final yield of purified Rap-DDD2 was 10 mg/L of culture.

The DNL method was employed to rapidly generate a panel of IgG-Rap conjugates. The IgG-AD modules were expressed in myeloma cells and purified from the culture supernatant using Protein A affinity chromatography. The Rap-DDD2 module was produced and mixed with IgG-AD2 to form a DNL complex. Since the CH3-AD2-IgG modules possess two AD2 peptides and each can tether a Rap dimer, the resulting IgG-Rap DNL construct comprises four Rap groups and one IgG. IgG-Rap is formed nearly quantitatively from the constituent modules and purified to near homogeneity with Protein A.

Prior to the DNL reaction, the CH3-AD2-IgG exists as both a monomer, and a disulfide-linked dimer (not shown). Under non-reducing conditions, the IgG-Rap resolves as a cluster of high molecular weight bands of the expected size between those for monomeric and dimeric CH3-AD2-IgG (not shown). Reducing conditions, which reduces the conjugates to their constituent polypeptides, shows the purity of the IgG-Rap and the consistency of the DNL method, as only bands representing heavy-chain-AD2 (HC-AD2), kappa light chain and Rap-DDD2 were visualized (not shown).

Reversed phase HPLC analysis of 22-Rap (not shown) resolved a single protein peak at 9.10 min eluting between the two peaks of CH3-AD2-IgG-hLL2, representing the monomeric (7.55 min) and the dimeric (8.00 min) forms. The Rap-DDD2 module was isolated as a mixture of dimer and tetramer (reduced to dimer during DNL), which were eluted at 9.30 and 9.55 min, respectively (not shown).

LC/MS analysis of 22-Rap was accomplished by coupling reversed phase HPLC using a C8 column with ESI-TOF mass spectrometry (not shown). The spectrum of unmodified 22-Rap identifies two major species, having either two G0F (G0F/G0F) or one G0F plus one G1F (G0F/G1F) N-linked glycans, in addition to some minor glycoforms (not shown). Enzymatic deglycosylation resulted in a single deconvoluted mass consistent with the calculated mass of 22-Rap (not shown). The resulting spectrum following reduction with TCEP identified the heavy chain-AD2 polypeptide modified with an N-linked glycan of the G0F or G1F structure as well as additional minor forms (not shown). Each of the three subunit polypeptides comprising 22-Rap were identified in the deconvoluted spectrum of the reduced and deglycosylated sample (not shown). The results confirm that both the Rap-DDD2 and HC-AD2 polypeptides have an amino terminal glutamine that is converted to pyroglutamate (pQ); therefore, 22-Rap has 6 of its 8 constituent polypeptides modified by pQ.

In vitro cytotoxicity was evaluated in three NHL cell lines. Each cell line expresses CD20 at a considerably higher surface density compared to CD22; however, the internalization rate for hLL2 (anti-CD22) is much faster than hA20 (anti-CD20). 14-Rap shares the same structure as 22-Rap and 20-Rap, but its antigen (CEACAM5) is not expressed by the NHL cells. Cells were treated continuously with IgG-Rap as single agents or with combinations of the parental MAbs plus rRap. Both 20-Rap and 22-Rap killed each cell line at concentrations above 1 nM, indicating that their action is cytotoxic as opposed to merely cytostatic (not shown). 20-Rap was the most potent IgG-Rap, suggesting that antigen density may be more important than internalization rate. Similar results were obtained for Daudi and Ramos, where 20-Rap (EC50-0.1 nM) was 3-6-fold more potent than 22-Rap (not shown). The rituximab-resistant mantle cell lymphoma line, Jeko-1, exhibits increased CD20 but decreased CD22, compared to Daudi and Ramos. Importantly, 20-Rap exhibited very potent cytotoxicity (EC₅₀˜20 pM) in Jeko-1, which was 25-fold more potent than 22-Rap (not shown).

The DNL method provides a modular approach to efficiently tether multiple cytotoxins onto a targeting antibody, resulting in novel immunotoxins that are expected to show higher in vivo potency due to improved pharmacokinetics and targeting specificity. LC/MS, RP-HPLC and SDS-PAGE demonstrated the homogeneity and purity of IgG-Rap. Targeting Rap with a MAb to a cell surface antigen enhanced its tumor-specific cytotoxicity. Antigen density and internalization rate are both critical factors for the observed in vitro potency of IgG-Rap. In vitro results show that CD20-, CD22-, or HLA-DR-targeted IgG-Rap have potent biologic activity for therapy of B-cell lymphomas and leukemias.

Example 12. Production and Use of a DNL Construct Comprising Two Different Antibody Moieties and a Cytokine

In certain embodiments, trimeric DNL constructs may comprise three different effector moieties, for example two different antibody moieties and a cytokine moiety. We report here the generation and characterization of the first bispecific MAb-IFNα, designated 20-C2-2b, which comprises two copies of IFN-α2b and a stabilized F(ab)₂ of hL243 (humanized anti-HLA-DR; IMMU-114) site-specifically linked to veltuzumab (humanized anti-CD20). In vitro, 20-C2-2b inhibited each of four lymphoma and eight myeloma cell lines, and was more effective than monospecific CD20-targeted MAb-IFNα or a mixture comprising the parental antibodies and IFNα in all but one (HLA-DR⁻/CD20⁻) myeloma line (not shown), suggesting that 20-C2-2b should be useful in the treatment of various hematopoietic disorders. The 20-C2-2b displayed greater cytotoxicity against KMS 12-BM (CD20⁺/HLA-DR⁺ myeloma) than monospecific MAb-IFNα that targets only HLA-DR or CD20 (not shown), indicating that all three components in 20-C2-2b can contribute to toxicity. Our findings indicate that a given cell's responsiveness to MAb-IFNα depends on its sensitivity to IFNα and the specific antibodies, as well as the expression and density of the targeted antigens.

Because 20-C2-2b has antibody-dependent cellular cytotoxicity (ADCC), but not CDC, and can target both CD20 and HLA-DR, it is useful for therapy of a broad range of hematopoietic disorders that express either or both antigens.

Antibodies

The abbreviations used in the following discussion are: 20 (C_(H)3-AD2-IgG-v-mab, anti-CD20 IgG DNL module); C2 (C_(H)1-DDD2-Fab-hL243, anti-HLA-DR Fab₂ DNL module); 2b (dimeric IFNα2B-DDD2 DNL module); 734 (anti-in-DTPA IgG DNL module used as non-targeting control). The following MAbs were provided by Immunomedics, Inc.: veltuzumab or v-mab (anti-CD20 IgG₁), hL243γ4p (Immu-114, anti-HLA-DR IgG₄), a murine anti-IFNα MAb, and rat anti-idiotype MAbs to v-mab (WR2) and hL243 (WT).

DNL Constructs

Monospecific MAb-IFNα (20-2b-2b, 734-2b-2b and C2-2b-2b) and the bispecific HexAb (20-C2-C2) were generated by combination of an IgG-AD2-module with DDD2-modules using the DNL method, as described in the preceding Examples. The 734-2b-2b, which comprises tetrameric IFNα2b and MAb h734 [anti-Indium-DTPA IgG₁], was used as a non-targeting control MAb-IFNα.

The construction of the mammalian expression vector as well as the subsequent generation of the production clones and the purification of C_(H)3-AD2-IgG-v-mab are disclosed in the preceding Examples. The expressed recombinant fusion protein has the AD2 peptide linked to the carboxyl terminus of the C_(H)3 domain of v-mab via a 15 amino acid long flexible linker peptide. Co-expression of the heavy chain-AD2 and light chain polypeptides results in the formation of an IgG structure equipped with two AD2 peptides. The expression vector was transfected into Sp/ESF cells (an engineered cell line of Sp2/0) by electroporation. The pdHL2 vector contains the gene for dihydrofolate reductase, thus allowing clonal selection, as well as gene amplification with methotrexate (MTX). Stable clones were isolated from 96-well plates selected with media containing 0.2 μM MTX. Clones were screened for C_(H)3-AD2-IgG-vmab productivity via a sandwich ELISA. The module was produced in roller bottle culture with serum-free media.

The DDD-module, IFNα2b-DDD2, was generated as discussed above by recombinant fusion of the DDD2 peptide to the carboxyl terminus of human IFNα2b via an 18 amino acid long flexible linker peptide. As is the case for all DDD-modules, the expressed fusion protein spontaneously forms a stable homodimer.

The C_(H)1-DDD2-Fab-hL243 expression vector was generated from hL243-IgG-pdHL2 vector by excising the sequence for the C_(H)1-Hinge-C_(H)2-C_(H)3 domains with SacII and EagI restriction enzymes and replacing it with a 507 bp sequence encoding C_(H)1-DDD2, which was excised from the C-DDD2-hMN-14-pdHL2 expression vector with the same enzymes. Following transfection of C_(H)1-DDD2-Fab-hL243-pdHL2 into Sp/ESF cells by electroporation, stable, MTX-resistant clones were screened for productivity via a sandwich ELISA using 96-well microtiter plates coated with mouse anti-human kappa chain to capture the fusion protein, which was detected with horseradish peroxidase-conjugated goat anti-human Fab. The module was produced in roller bottle culture.

Roller bottle cultures in serum-free H-SFM media and fed-batch bioreactor production resulted in yields comparable to other IgG-AD2 modules and cytokine-DDD2 modules generated to date. C_(H)3-AD2-IgG-v-mab and IFNα2b-DDD2 were purified from the culture broths by affinity chromatography using MABSELECT™ (GE Healthcare) and HIS-SELECT® HF Nickel Affinity Gel (Sigma), respectively, as described previously (Rossi et al., Blood 2009, 114:3864-71). The culture broth containing the C_(H)1-DDD2-Fab-hL243 module was applied directly to KAPPASELECT® affinity gel (GE-Healthcare), which was washed to baseline with PBS and eluted with 0.1M Glycine, pH 2.5.

The purity of the DNL modules was assessed by SDS-PAGE and SE-HPLC (not shown). Analysis under non-reducing conditions showed that, prior to the DNL reaction, IFNα2b-DDD2 and C_(H)1-DDD2-Fab-hL243 exist as disulfide-linked dimers (not shown). This phenomenon, which is always seen with DDD-modules, is beneficial, as it protects the reactive sulfhydryl groups from irreversible oxidation. In comparison, C_(H)3-AD2-IgG-v-mab (not shown) exists as both a monomer and a disulfide-linked dimer, and is reduced to monomer during the DNL reaction. SE-HPLC analyses agreed with the non-reducing SDS-PAGE results, indicating monomeric species as well as dimeric modules that were converted to monomeric forms upon reduction (not shown). The sulfhydryl groups are protected in both forms by participation in disulfide bonds between AD2 cysteine residues. Reducing SDS-PAGE demonstrated that each module was purified to near homogeneity and identified the component polypeptides comprising each module (not shown). For C_(H)3-AD2-IgG-v-mab, heavy chain-AD2 and kappa light chains were identified. hL243-Fd-DDD2 and kappa light chain polypeptides were resolved for C_(H)1-DDD2-Fab-hL243 (not shown). One major and one minor band were resolved for IFNα2b-DDD2 (not shown), which were determined to be non-glycosylated and O-glycosylated species, respectively.

Generation of 20-C2-2b by DNL

Three DNL modules (C_(H)3-AD2-IgG-v-mab, C_(H)1-DDD2-Fab-hL243, and IFN-α2b-DDD2) were combined in equimolar quantities to generate the bsMAb-IFNα, 20-C2-2b. Following an overnight docking step under mild reducing conditions (1 mM reduced glutathione) at room temperature, oxidized glutathione was added (2 mM) to facilitate disulfide bond formation (locking) The 20-C2-2b was purified to near homogeneity using three sequential affinity chromatography steps. Initially, the DNL mixture was purified with Protein A (MABSELECT™), which binds the C_(H)3-AD2-IgG-v-MAb group and eliminates un-reacted IFNα2b-DDD2 or C_(H)1-DDD2-Fab-hL243. The Protein A-bound material was further purified by IMAC using HIS-SELECT® HF Nickel Affinity Gel, which binds specifically to the IFNα2b-DDD2 moiety and eliminates any constructs lacking this group. The final process step, using an hL243-anti-idiotype affinity gel removed any molecules lacking C_(H)1-DDD2-Fab-hL243.

The skilled artisan will realize that affinity chromatography may be used to purify DNL complexes comprising any combination of effector moieties, so long as ligands for each of the three effector moieties can be obtained and attached to the column material. The selected DNL construct is the one that binds to each of three columns containing the ligand for each of the three effector moieties and can be eluted after washing to remove unbound complexes.

The following Example is representative of several similar preparations of 20-C2-2b. Equimolar amounts of C_(H)3-AD2-IgG-v-mab (15 mg), C_(H)1-DDD2-Fab-hL243 (12 mg), and IFN-α2b-DDD2 (5 mg) were combined in 30-mL reaction volume and 1 mM reduced glutathione was added to the solution. Following 16 h at room temperature, 2 mM oxidized glutathione was added to the mixture, which was held at room temperature for an additional 6 h. The reaction mixture was applied to a 5-mL Protein A affinity column, which was washed to baseline with PBS and eluted with 0.1M Glycine, pH 2.5. The eluate, which contained ˜20 mg protein, was neutralized with 3M Tris-HCl, pH 8.6 and dialyzed into HIS-SELECT® binding buffer (10 mM imidazole, 300 mM NaCl, 50 mM NaH₂PO₄, pH 8.0) prior to application to a 5-mL HIS-SELECT® IMAC column. The column was washed to baseline with binding buffer and eluted with 250 mM imidazole, 150 mM NaCl, 50 mM NaH₂PO₄, pH 8.0.

The IMAC eluate, which contained ˜11.5 mg of protein, was applied directly to a WP (anti-hL243) affinity column, which was washed to baseline with PBS and eluted with 0.1M glycine, pH 2.5. The process resulted in 7 mg of highly purified 20-C2-2b. This was approximately 44% of the theoretical yield of 20-C2-2b, which is 50% of the total starting material (16 mg in this example) with 25% each of 20-2b-2b and 20-C2-C2 produced as side products.

Generation and Characterization of 20-C2-2b

The bispecific MAb-IFNα was generated by combining the IgG-AD2 module, C_(H)3-AD2-IgG-v-mab, with two different dimeric DDD-modules, C_(H)1-DDD2-Fab-hL243 and IFNα2b-DDD2. Due to the random association of either DDD-module with the two AD2 groups, two side-products, 20-C2-C2 and 20-2b-2b are expected to form, in addition to 20-C2-2b.

Non-reducing SDS-PAGE (not shown) resolved 20-C2-2b (˜305 kDa) as a cluster of bands positioned between those of 20-C2-C2 (˜365 kDa) and 20-2b-2b (255 kDa). Reducing SDS-PAGE resolved the five polypeptides (v-mab HC-AD2, hL243 Fd-DDD2, IFNα2b-DDD2 and co-migrating v-mab and hL243 kappa light chains) comprising 20-C2-2b (not shown). IFNα2b-DDD2 and hL243 Fd-DDD2 are absent in 20-C2-C2 and 20-2b-2b. MABSELECT™ binds to all three of the major species produced in the DNL reaction, but removes any excess IFNα2b-DDD2 and C_(H)1-DDD2-Fab-hL243. The HIS-SELECT® unbound fraction contained mostly 20-C2-C2 (not shown). The unbound fraction from WT affinity chromatography comprised 20-2b-2b (not shown). Each of the samples was subjected to SE-HPLC and immunoreactivity analyses, which corroborated the results and conclusions of the SDS-PAGE analysis.

Following reduction of 20-C2-2b, its five component polypeptides were resolved by RP-HPLC and individual ESI-TOF deconvoluted mass spectra were generated for each peak (not shown). Native, but not bacterially-expressed recombinant IFNα2, is O-glycosylated at Thr-106 (Adolf et al., Biochem J 1991; 276 (Pt 2):511-8). We determined that ˜15% of the polypeptides comprising the IFNα2b-DDD2 module are O-glycosylated and can be resolved from the non-glycosylated polypeptides by RP-HPLC and SDS-PAGE (not shown). LC/MS analysis of 20-C2-2b identified both the O-glycosylated and non-glycosylated species of IFNα2b-DDD2 with mass accuracies of 15 ppm and 2 ppm, respectively (not shown). The observed mass of the O-glycosylated form indicates an O-linked glycan having the structure NeuGc-NeuGc-Gal-GalNAc, which was also predicted (<1 ppm) for 20-2b-2b (not shown). LC/MS identified both v-mab and hL243 kappa chains as well as hL243-Fd-DDD2 (not shown) as single, unmodified species, with observed masses matching the calculated ones (<35 ppm). Two major glycoforms of v-mab HC-AD2 were identified as having masses of 53,714.73 (70%) and 53,877.33 (30%), indicating G0F and G1F N-glycans, respectively, which are typically associated with IgG (not shown). The analysis also confirmed that the amino terminus of the HC-AD2 is modified to pyroglutamate, as predicted for polypeptides having an amino terminal glutamine.

SE-HPLC analysis of 20-C2-2b resolved a predominant protein peak with a retention time (6.7 min) consistent with its calculated mass and between those of the larger 20-C2-C2 (6.6 min) and smaller 20-2b-2b (6.85 min), as well as some higher molecular weight peaks that likely represent non-covalent dimers formed via self-association of IFNα2b (not shown).

Immunoreactivity assays demonstrated the homogeneity of 20-C2-2b with each molecule containing the three functional groups (not shown). Incubation of 20-C2-2b with an excess of antibodies to any of the three constituent modules resulted in quantitative formation of high molecular weight immune complexes and the disappearance of the 20-C2-2b peak (not shown). The HIS-SELECT® and WT affinity unbound fractions were not immunoreactive with WT and anti-IFNα, respectively (not shown). The MAb-IFNα showed similar binding avidity to their parental MAbs (not shown).

IFNα Biological Activity

The specific activities for various MAb-IFNα were measured using a cell-based reporter gene assay and compared to peginterferon alfa-2b (not shown). Expectedly, the specific activity of 20-C2-2b (2454 IU/pmol), which has two IFNα2b groups, was significantly lower than those of 20-2b-2b (4447 IU/pmol) or 734-2b-2b (3764 IU/pmol), yet greater than peginterferon alfa-2b (P<0.001) (not shown). The difference between 20-2b-2b and 734-2b-2b was not significant. The specific activity among all agents varies minimally when normalized to IU/pmol of total IFNα. Based on these data, the specific activity of each IFNα2b group of the MAb-IFNα is approximately 30% of recombinant IFNα2b (˜4000 IU/pmol).

In the ex-vivo setting, the 20-C2-2b DNL construct depleted lymphoma cells more effectively than normal B cells and had no effect on T cells (not shown). However, it did efficiently eliminate monocytes (not shown). Where v-mab had no effect on monocytes, depletion was observed following treatment with hL243α4p and MAb-IFNα, with 20-2b-2b and 734-2b-2b exhibiting similar toxicity (not shown). Therefore, the predictably higher potency of 20-C2-2b is attributed to the combined actions of anti-HLA-DR and IFNα, which may be augmented by HLA-DR targeting. These data suggest that monocyte depletion may be a pharmacodynamic effect associated anti-HLA-DR as well as IFNα therapy; however, this side affect would likely be transient because the monocyte population should be repopulated from hematopoietic stem cells.

The skilled artisan will realize that the approach described here to produce and use bispecific immunocytokine, or other DNL constructs comprising three different effector moieties, may be utilized with any combinations of antibodies, antibody fragments, cytokines or other effectors that may be incorporated into a DNL construct, for example the combination of anti-CD20 and anti-CD22 with IFNα2b.

Example 13. Hexavalent DNL Constructs

The DNL technology described above for formation of trivalent DNL complexes was applied to generate hexavalent IgG-based DNL structures (HIDS). Because of the increased number of binding sites for target antigens, hexavalent constructs might be expected to show greater affinity and/or efficacy against target cells. Two types of modules, which were produced as recombinant fusion proteins, were combined to generate a variety of HIDS. Fab-DDD2 modules were as described for use in generating trivalent Fab structures (Rossi et al. Proc Natl Acad Sci USA 0.2006; 103(18): 6841-6). The Fab-DDD2 modules form stable homodimers that bind to AD2-containing modules. To generate HIDS, two types of IgG-AD2 modules were created to pair with the Fab-DDD2 modules: C-H-AD2-IgG and N-L-AD2-IgG.

C-H-AD2-IgG modules have an AD2 peptide fused to the carboxyl terminus (C) of the heavy (H) chain of IgG via a peptide linker. The DNA coding sequences for the linker peptide followed by the AD2 peptide are coupled to the 3′ end of the CH₃ (heavy chain constant domain 3) coding sequence by standard recombinant DNA methodologies, resulting in a contiguous open reading frame. When the heavy chain-AD2 polypeptide is co-expressed with a light chain polypeptide, an IgG molecule is formed possessing two AD2 peptides, which can therefore bind two Fab-DDD2 dimers. The C-H-AD2-IgG module can be combined with any Fab-DDD2 module to generate a wide variety of hexavalent structures composed of an Fc fragment and six Fab fragments. If the C-H-AD2-IgG module and the Fab-DDD2 module are derived from the same parental monoclonal antibody (MAb) the resulting HIDS is monospecific with 6 binding arms to the same antigen. If the modules are instead derived from two different MAbs then the resulting HIDS are bispecific, with two binding arms for the specificity of the C-H-AD2-IgG module and 4 binding arms for the specificity of the Fab-DDD2 module.

N-L-AD2-IgG is an alternative type of IgG-AD2 module in which an AD2 peptide is fused to the amino terminus (N) of the light (L) chain of IgG via a peptide linker. The L chain can be either Kappa (K) or Lambda (λ) and will also be represented as K. The DNA coding sequences for the AD2 peptide followed by the linker peptide are coupled to the 5′ end of the coding sequence for the variable domain of the L chain (V_(L)), resulting in a contiguous open reading frame. When the AD2-kappa chain polypeptide is co-expressed with a heavy chain polypeptide, an IgG molecule is formed possessing two AD2 peptides, which can therefore bind two Fab-DDD2 dimers. The N-L-AD2-IgG module can be combined with any Fab-DDD2 module to generate a wide variety of hexavalent structures composed of an Fc fragment and six Fab fragments.

The same technique has been utilized to produce DNL complexes comprising an IgG moiety attached to four effector moieties, such as cytokines. In an exemplary embodiment, an IgG moiety was attached to four copies of interferon-α2b. The antibody-cytokine DNL construct exhibited superior pharmacokinetic properties and/or efficacy compared to PEGylated forms of interferon-α2b.

Example 14. Creation of C-H-AD2-IgG-pdHL2 Expression Vectors

The pdHL2 mammalian expression vector has been used to mediate the expression of many recombinant IgGs. A plasmid shuttle vector was produced to facilitate the conversion of any IgG-pdHL2 vector into a C-H-AD2-IgG-pdHL2 vector. The gene for the Fc (CH2 and CH3 domains) was amplified using the pdHL2 vector as a template and a pair of primers. The amplimer was cloned in the PGEMT® PCR cloning vector. The Fc insert fragment was excised from PGEMT® with XbaI and BamHI restriction enzymes and ligated with AD2-pdHL2 vector that was prepared by digestion of h679-Fab-AD2-pdHL2 with XbaI and BamHI, to generate the shuttle vector Fc-AD2-pdHL2.

To convert any IgG-pdHL2 expression vector to a C-H-AD2-IgG-pdHL2 expression vector, an 861 bp BsrGI/NdeI restriction fragment is excised from the former and replaced with a 952 bp BsrGI/NdeI restriction fragment excised from the Fc-AD2-pdHL2 vector. BsrGI cuts in the CH3 domain and NdeI cuts downstream (3′) of the expression cassette.

Example 15. Production of AD2-Linked IgG Species

Production of C-H-AD2-hLL2 IgG

Epratuzumab, or hLL2 IgG, is a humanized anti-human CD22 MAb. An expression vector for C-H-AD2-hLL2 IgG was generated from hLL2 IgG-pdHL2, as described above, and used to transfect Sp2/0 myeloma cells by electroporation. Following transfection, the cells were plated in 96-well plates and transgenic clones were selected in media containing methotrexate. Clones were screened for C-H-AD2-hLL2 IgG productivity by a sandwich ELISA using 96-well microtiter plates coated with an hLL2-specific anti-idiotype MAb and detection with peroxidase-conjugated anti-human IgG. Clones were expanded to roller bottles for protein production and C-H-AD2-hLL2 IgG was purified from the spent culture media in a single step using Protein-A affinity chromatography. SE-HPLC analysis resolved two protein peaks (not shown). The retention time of the slower eluted peak was similar to hLL2 IgG (not shown). The retention time of the faster eluted peak was consistent with a ˜300 kDa protein (not shown). It was later determined that this peak represents disulfide linked dimers of C-H-AD2-hLL2-IgG. This dimer is reduced to the monomeric form during the DNL reaction. SDS-PAGE analysis demonstrated that the purified C-H-AD2-hLL2-IgG consisted of both monomeric and disulfide-linked dimeric forms of the module (not shown). Protein bands representing these two forms are evident by SDS-PAGE under non-reducing conditions, while under reducing conditions all of the forms are reduced to two bands representing the constituent polypeptides (Heavy chain-AD2 and kappa chain) (not shown). No other contaminating bands were detected.

Production of C-H-AD2-hA20 IgG

hA20 IgG is a humanized anti-human CD20 MAb. An expression vector for C-H-AD2-hA20 IgG was generated from hA20 IgG-pDHL2, as described above, and used to transfect Sp2/0 myeloma cells by electroporation. Following transfection, the cells were plated in 96-well plates and transgenic clones were selected in media containing methotrexate. Clones were screened for C-H-AD2-hA20 IgG productivity by a sandwich ELISA using 96-well microtiter plates coated with a hA20-specific anti-idiotype MAb and detection with peroxidase-conjugated anti-human IgG. Clones were expanded to roller bottles for protein production and C-H-AD2-hA20 IgG was purified from the spent culture media in a single step using Protein-A affinity chromatography. SE-HPLC and SDS-PAGE analyses gave very similar results to those obtained for C-H-AD2-hLL2 IgG (not shown).

Production of N-L-AD2-hA20 IgG

A 197 bp DNA duplex comprising the coding sequence for the light chain leader peptide, AD2, a 13-residue peptide linker and the first four residues of hA20 Vk (all in frame) was generated as follows. Two 100-mer synthetic oligonucleotides, which overlap by 35 base-pairs, were made fully duplex by primer extension using Taq polymerase. The sequence was amplified by PCR, which appended XbaI and PvuII restriction sites to the 5′ and 3′ ends, respectively. The amplimer was cloned into PGEMT®.

The 197 bp XbaI/PvuII fragment was excised from PGEMT® and ligated with the hA20 V_(K) shuttle vector h2B8-V_(k)-pBR2, which was prepared by digestion with XbaI and PvuII. The new shuttle vector is AD2-K-hA20-pBR2. A 536 bp XbaI/Bam HI restriction fragment was excised from AD2-K-hA20-pBR2 and ligated with hA20-IgG-pDHL2 vector that was prepared by digestion with XbaI and Bam HI to generate the expression vector N-L-AD2-hA20-IgG-pdHL2.

N-L-AD2-hA20-IgG-pdHL2 was used to transfect Sp2/0 myeloma cells by electroporation. Following transfection, the cells were plated in 96-well plates and transgenic clones were selected in media containing methotrexate. Clones were screened for N-L-AD2-hA20 IgG productivity by a sandwich ELISA using 96-well microtiter plates coated with a hA20-specific anti-idiotype MAb and detection with peroxidase-conjugated anti-human IgG. Clones were expanded to roller bottles for protein production and N-L-AD2-hA20 IgG was purified from the spent culture media in a single step using Protein-A affinity chromatography.

Size exclusion HPLC showed that the majority of the N-L-AD2-hA20 IgG in the prep is in a monomeric form with a retention time similar to IgG (not shown). Two additional peaks likely representing disulfide linked dimeric and trimeric forms and each accounting for approximately 15% of the total protein were also observed (not shown). Mild reduction of the prep, as is used in the DNL reaction, resulted in the conversion of the dimeric and trimeric forms to the monomeric form (not shown).

Example 16. Generation of Hexavalent DNL Constructs

Generation of Hex-hA20

The DNL method was used to create Hex-hA20, a monospecific anti-CD20 HIDS, by combining C-H-AD2-hA20 IgG with hA20-Fab-DDD2. The Hex-hA20 structure contains six anti-CD20 Fab fragments and an Fc fragment, arranged as four Fab fragments and one IgG antibody. Hex-hA20 was made in four steps.

Step 1, Combination:

A 210% molar equivalent of (hA20-Fab-DDD2)₂ was mixed with C-H-AD2-hA20 IgG. This molar ratio was used because two Fab-DDD2 dimers are coupled to each C-H-AD2-hA20 IgG molecule and an additional 10% excess of the former ensures that the coupling reaction is complete. The molecular weights of C-H-AD2-hA20 IgG and (hA20-Fab-DDD2)₂ are 168 kDa and 107 kDa, respectively. As an example, 134 mg of hA20-Fab-DDD2 would be mixed with 100 mg of C-H-AD2-hA20 IgG to achieve a 210% molar equivalent of the former. The mixture is typically made in phosphate buffered saline, pH 7.4 (PBS) with 1 mM EDTA.

Step 2, Mild Reduction:

Reduced glutathione (GSH) was added to a final concentration of 1 mM and the solution is held at room temperature (16-25° C.) for 1-24 hours.

Step 3, Mild Oxidation:

Following reduction, oxidized glutathione (GSSH) was added directly to the reaction mixture to a final concentration of 2 mM and the solution was held at room temperature for 1-24 hours.

Step 4, Isolation of the DNL Product:

Following oxidation, the reaction mixture was loaded directly onto a Protein-A affinity chromatography column. The column was washed with PBS and the Hex-hA20 was eluted with 0.1M glycine, pH 2.5. Since excess hA20-Fab-DDD2 was used in the reaction, there was no unconjugated C-H-AD2-hA20 IgG, or incomplete DNL structures containing only one (hA20-Fab-DDD2)₂ moiety. The unconjugated excess hA20-Fab-DDD2 does not bind to the affinity resin. Therefore, the Protein A-purified material contains only the desired product.

The calculated molecular weight from the deduced amino acid sequences of the constituent polypeptides is 386 kDa. Size exclusion HPLC analysis showed a single protein peak with a retention time consistent with a protein structure of 375-400 kDa (not shown). SDS-PAGE analysis under non-reducing conditions showed a cluster of high molecular weight bands indicating a large covalent structure (not shown). SDS-PAGE under reducing conditions showed the presence of only the three expected polypeptide chains: the AD2-fused heavy chain (HC-AD2), the DDD2-fused Fd chain (Fd-DDD2), and the kappa chains (not shown).

Generation of Hex-hLL2

The DNL method was used to create a monospecific anti-CD22 HIDS (Hex-hLL2) by combining C-H-AD2-hLL2 IgG with hLL2-Fab-DDD2. The DNL reaction was accomplished as described above for Hex-hA20. The calculated molecular weight from the deduced amino acid sequences of the constituent polypeptides is 386 kDa. Size exclusion HPLC analysis showed a single protein peak with a retention time consistent with a protein structure of 375-400 kDa (not shown). SDS-PAGE analysis under non-reducing conditions showed a cluster of high molecular weight bands, which were eliminated under reducing conditions to leave only the three expected polypeptide chains: HC-AD2, Fd-DDD2, and the kappa chain (not shown).

Generation of DNL1 and DNL

The DNL method was used to create bispecific HIDS by combining C-H-AD2-hLL2 IgG with either hA20-Fab-DDD2 to obtain DNL1 or hMN-14-DDD2 to obtain DNL1C. DNL1 has four binding arms for CD20 and two for CD22. As hMN-14 is a humanized MAb to carcinoembryonic antigen (CEACAM5), DNL1C has four binding arms for CEACAM5 and two for CD22. The DNL reactions were accomplished as described for Hex-hA20 above.

For both DNL1 and DNL1C, the calculated molecular weights from the deduced amino acid sequences of the constituent polypeptides are ˜386 kDa. Size exclusion HPLC analysis showed a single protein peak with a retention time consistent with a protein structure of 375-400 kDa for each structure (not shown). SDS-PAGE analysis under non-reducing conditions showed a cluster of high molecular weight bands, which were eliminated under reducing conditions to leave only the three expected polypeptides: HC-AD2, Fd-DDD2, and the kappa chain (not shown).

Generation of DNL2 and DNL2C

The DNL method was used to create bispecific HIDS by combining C-H-AD2-hA20 IgG with either hLL2-Fab-DDD2 to obtain DNL2 or hMN-14-DDD2 to obtain DNL2C. DNL2 has four binding arms for CD22 and two for CD20. DNL2C has four binding arms for CEACAM5 and two for CD20. The DNL reactions were accomplished as described for Hex-hA20.

For both DNL2 and DNL2C, the calculated molecular weights from the deduced amino acid sequences of the constituent polypeptides are ˜386 kDa. Size exclusion HPLC analysis showed a single protein peak with a retention time consistent with a protein structure of 375-400 kDa for each structure (not shown). SDS-PAGE analysis under non-reducing conditions showed high molecular weight bands, but under reducing conditions consisted solely of the three expected polypeptides: HC-AD2, Fd-DDD2, and the kappa chain (not shown).

Generation of K-Hex-hA20

The DNL method was used to create a monospecific anti-CD20 HIDS (K-Hex-hA20) by combining N-L-AD2-hA20 IgG with hA20-Fab-DDD2. The DNL reaction was accomplished as described above for Hex-hA20.

The calculated molecular weight from the deduced amino acid sequences of the constituent polypeptides is 386 kDa. SDS-PAGE analysis under non-reducing conditions showed a cluster of high molecular weight bands, which under reducing conditions were composed solely of the four expected polypeptides: Fd-DDD2, H-chain, kappa chain, and AD2-kappa (not shown).

Generation of DNL3

A bispecific HIDS was generated by combining N-L-AD2-hA20 IgG with hLL2-Fab-DDD2. The DNL reaction was accomplished as described above for Hex-hA20. The calculated molecular weight from the deduced amino acid sequences of the constituent polypeptides is 386 kDa. Size exclusion HPLC analysis showed a single protein peak with a retention time consistent with a protein structure of 375-400 kDa (not shown). SDS-PAGE analysis under non-reducing conditions showed a cluster of high molecular weight bands that under reducing conditions showed only the four expected polypeptides: Fd-DDD2, H-chain, kappa chain, and AD2-kappa (not shown).

Stability in Serum

The stability of DNL1 and DNL2 in human serum was determined using a bispecific ELISA assay. The protein structures were incubated at 10 μg/ml in fresh pooled human sera at 37° C. and 5% CO₂ for five days. For day 0 samples, aliquots were frozen in liquid nitrogen immediately after dilution in serum. ELISA plates were coated with an anti-Id to hA20 IgG and bispecific binding was detected with an anti-Id to hLL2 IgG. Both DNL1 and DNL2 were highly stable in serum and maintained complete bispecific binding activity (not shown).

Binding Activity

The HIDS generated as described above retained the binding properties of their parental Fab/IgGs. Competitive ELISAs were used to investigate the binding avidities of the various HIDS using either a rat anti-idiotype MAb to hA20 (WR2) to assess the binding activity of the hA20 components or a rat anti-idiotype MAb to hLL2 (WN) to assess the binding activity of the hLL2 components. To assess hA20 binding, ELISA plates were coated with hA20 IgG and the HIDS were allowed to compete with the immobilized IgG for WR2 binding. To assess hLL2 binding, plates were coated with hLL2 IgG and the HIDS were allowed to compete with the immobilized IgG for WN binding. The relative amount of anti-Id bound to the immobilized IgG was detected using peroxidase-conjugated anti-Rat IgG.

Examining the relative CD20 binding avidities (FIG. 1A), DNL2, which has two CD20 binding groups, showed a similar binding avidity to hA20 IgG, which also has two CD20-binding arms (FIG. 1A). DNL1, which has four CD20-binding groups, had a stronger (˜4-fold) relative avidity than DNL2 or hA20 IgG (FIG. 1A). Hex-hA20, which has six CD20-binding groups, had an even stronger (˜10-fold) relative avidity than hA20 IgG (FIG. 1A).

Similar results were observed for CD22 binding (FIG. 1B). DNL1, which has two CD20 binding groups, showed a similar binding avidity to hLL2 IgG, which also has two CD22-binding arms (FIG. 1B). DNL2, which has four CD22-binding groups, had a stronger (>5-fold) relative avidity than DNL1 or hLL2 IgG. Hex-hLL2, which has six CD22-binding groups, had an even stronger (>10-fold) relative avidity than hLL2 IgG (FIG. 1B).

As both DNL2 and DNL3 contain two hA20 Fabs and four hLL2 Fabs, they showed similar strength in binding to the same anti-id antibody (not shown).

Some of the HIDS were observed to have potent anti-proliferative activity on lymphoma cell lines. DNL1, DNL2 and Hex-hA20 inhibited cell growth of Daudi Burkitt Lymphoma cells in vitro (FIG. 2). Treatment of the cells with 10 nM concentrations was substantially more effective for the HIDS compared to rituximab (not shown). Using a cell counting assay, the potency of DNL1 and DNL2 was estimated to be more than 100-fold greater than that of rituximab, while the Hex-hA20 was shown to be even more potent (not shown). This was confirmed with an MTS proliferation assay in which dose-response curves were generated for Daudi cells treated with a range of concentrations of the HIDS (not shown). Compared to rituximab, the bispecific HIDS (DNL1 and DNL2) and Hex-hA20 were >100-fold and >10000-fold more potent, respectively.

Example 17. In Vivo Anti-Tumor Activity of Hexavalent DNL Constructs

The HIDS were shown to have therapeutic efficacy in vivo using a human Burkitt Lymphoma model in mice (FIG. 3). Low doses (12 μg) of DNL2 and Hex-hA20 more than doubled the survival times of tumor bearing mice. Treatment with higher doses (60 μg) resulted in long-term survivors.

Example 18. Comparative Effects of Hexavalent DNL Constructs and Parent IgG on Lymphoma Cell Lines

Dose-response curves for HIDS (DNL1, DNL2, Hex-hA20) versus a parent IgG (hA20 IgG) were compared for three different lymphoma cell lines (FIG. 4), using an MTS proliferation assay. In Daudi lymphoma cells (FIG. 4, top panel), the bispecific structures DNL1 (not shown) and DNL2 showed >100-fold more potent anti-proliferative activity and Hex-hA20 showed >10.000-fold more potent activity than the parent hA20 IgG. Hex-hLL2 and the control structures (DNL1-C and DNL2-C) had very little anti-proliferative activity in this assay (not shown).

In Raji lymphoma cells (FIG. 4, middle panel), Hex-hA20 displayed potent anti-proliferative activity, but DNL2 showed only minimal activity compared with hA20 IgG. In Ramos lymphoma cells (FIG. 4, bottom panel), both DNL2 and Hex-hA20 displayed potent anti-proliferative activity, compared with hA20 IgG. These results show that the increased potency of HIDS relative to the parent IgGs is not limited to particular cell lines, but rather is a general phenomenon for cells displaying the appropriate targets.

Example 19. CDC and ADCC Activity of Hexavalent DNL Constructs

In vivo, anti-CD20 monoclonal antibodies such as rituximab and hA20 can utilize complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC) and signal transduction induced growth inhibition/apoptosis for tumor cell killing. The hexavalent DNL structures (DNL1, DNL2, Hex-hA20) were tested for CDC activity using Daudi cells in an in vitro assay. Surprisingly, none of the hexavalent structures that bind CD20 exhibited CDC activity (not shown). The parent hA20 IgG exhibited potent CDC activity (not shown), while as expected the hLL2 antibody against CD22 showed no activity (not shown). The lack of effect of DNL2 and Hex-hA20 was of interest, since they comprise hA20-IgG-Ad2, which showed similar positive CDC activity to hA20 IgG (not shown).

DNL1 was assayed for ADCC activity using freshly isolated peripheral blood mononuclear cells. Both rituximab and hA20 IgG showed potent activity on Daudi cells, while DNL1 did not exhibit any detectable ADCC activity (not shown).

These data suggest that the Fc region may become inaccessible for effector functions (CDC and ADCC) when four additional Fab groups are tethered to its carboxyl termini. Therefore, the hexavalent DNL structures appear to rely only on signal transduction induced growth inhibition/apoptosis for in vivo anti-tumor activity.

Example 20. Multiple Signaling Pathways Induced by Hexavalent, Monospecific Anti-CD20 and Bispecific Anti-CD20/CD22 Antibodies Correlate with Enhanced Toxicity to B-Cell Lymphomas

We have generated hexavalent antibodies (HexAbs) comprising 6 Fabs tethered to one Fc of human IgG1. Three such constructs, 20-20, a monospecific HexAb comprising 6 Fabs of veltuzumab (humanized anti-CD20 immunoglobulin G1κ [IgG1κ]), 20-22, a bispecific HexAb comprising veltuzumab and 4 Fabs of epratuzumab (humanized anti-CD22 IgG1κ), and 22-20, a bispecific HexAb comprising epratuzumab and 4 Fabs of veltuzumab, were shown to inhibit proliferation of several lymphoma cell lines at nanomolar concentrations in the absence of a crosslinking antibody, as described in the Examples above. We report here a detailed analysis of the apoptotic and survival signals induced by the 3 HexAbs in Burkitt lymphomas and provide in vitro cytotoxicity data for additional lymphoma cell lines and also chronic lymphocytic leukemia patient specimens. Among the key findings are the significant increase in the levels of phosphorylated p38 and PTEN (phosphatase and tensin homolog deleted on chromosome 10) by all 3 HexAbs and notable differences in the signaling events triggered by the HexAbs from those incurred by crosslinking veltuzumab or rituximab with a secondary antibody. Thus, the greatly enhanced direct toxicity of these HexAbs correlates with their ability to alter the basal expression of various intracellular proteins involved in regulating cell growth, survival, and apoptosis, with the net outcome leading to cell death.

The goal of this study was to extend our in vitro characterization of 20-20, 20-22, and 22-20, with a primary interest in elucidating the intracellular signaling pathways involved in transducing CD20 upon ligating human lymphoma cells with each of these 3 HexAbs, and comparing the results with those obtained in parallel with epratuzumab, veltuzumab, and rituximab. Selective experiments were performed to determine whether the individual profile of the kinases activated by the anti-CD20/CD22 HexAbs would be similar to or different from that triggered by anti-IgM, or by crosslinking veltuzumab or rituximab with a secondary antibody. The data presented below allow us to correlate the enhanced direct cytotoxicity of the anti-CD20/CD22 HexAbs, compared with their bivalent parental antibodies, with their increased ability to up-regulate PTEN, phosphorylated p38 and cyclin-dependent kinase (CDK) inhibitors, as represented by p21, p27 and Kip2. The reasons for selecting 22-20 as the best lead among the 3 HexAbs for clinical evaluation also are discussed.

Methods

Antibodies and Reagents

The generation and preparation of 20-20, 20-22, and 22-20 was described above. Rituximab was obtained from commercial supplies. Mouse antihuman IgM was purchased from Southern Biotech. Other antibodies were from Cell Signaling or Santa Cruz Biotechnology. Horseradish peroxidase-conjugated secondary antibodies were obtained from Jackson ImmunoResearch Laboratories. Heat-inactivated fetal bovine serum was purchased from Hyclone. Cell culture media, supplements, tetramethylrhodamine ethyl ester, and the transfection reagent DMRIE-C were from Invitrogen Life Technologies. One Solution MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay reagent was obtained from Promega. Reducing 4%-20% gradient Tris-glycine gels were from Cambrex Bio Science Annexin V-ALEXA FLUOR® 488 conjugate for apoptosis detection was obtained from Invitrogen. All other chemicals were purchased from Sigma-Aldrich.

Cell Culture

Burkitt (Daudi, Raji) and non-Burkitt (RL and DoHH2) human lymphoma lines were obtained from ATCC and cultured at 37° C. in 5% CO₂ and RPMI 1640 medium supplemented with 10% heat-inactivated fetal bovine serum, 2 mM L-glutamine, 200 U/mL penicillin, and 100 μg/mL streptomycin. Cells from chronic lymphocytic leukemia (CLL) patients were collected from whole blood by FICOLL-HYPAQUE® separation (Stein et al., Blood 2010, 115:5180-5190) and grown in RPMI media as described above.

Cell Viability Assay

Cells were seeded at a density of 1×10⁵ cells/mL in 96-well plates (1×10⁴ cells/well) and incubated with each test antibody or DNL complex at a final concentration of 0.01-500 nM for 3 (Daudi) and 4 days (Raji, R L, and DoHH2). Where indicated, antibodies were cross-linked with a secondary goat anti-human (GAH) antibody at a concentration of 10 μg/mL. Patient CLL cells were seeded in 48-well plates at a density of 5×10⁵ cells/mL (1.5×10⁵ cells/well) and incubated with each test antibody at a final concentration of 10 nM for 3 days. The number of living cells was then determined using the soluble tetrazolium salt MTS following the manufacturer's protocol.

Annexin V Binding Assay

Cells in 6-well plates (2×10⁵ cells/well at 1×10⁵ cells/mL) were treated with each test antibody at 10 or 100 nM for 24 hours, washed, resuspended in 100 μL of annexin-binding buffer (10 mM HEPES [N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid], 140 mM NaCl, and 2.5 mM CaCl₂ in phosphate-buffered saline; PBS), stained with 5 μL of annexin V-ALEXA FLUOR® 488 conjugate for 20 minutes, followed by staining with 1 μg/mL of propidium iodide (PI) in 400 μL of annexin-binding buffer, and analyzed by flow cytometry (FACSCALIBUR®; Becton Dickinson). Cells stained positive with annexin V (including both PI-negative and -positive) were counted as apoptotic populations.

Cell-Cycle Analysis

Cells were seeded and treated with each test antibody as described for the annexin V binding assay, except that they were resuspended in 0.5 mL of a solution containing PI (50 μg/mL), sodium citrate (0.1%), and Triton X-100 (0.1%) and stained for 1 hour before analysis by flow cytometry.

Assessment of Mitochondrial Membrane Depolarization

Changes in mitochondrial transmembrane potential (Δψ_(m)) were determined by flow cytometry. Briefly, Daudi cells in E-well plates (2×10⁵ cells/well seeded at 1×10⁵ cells/mL) were incubated overnight (16 hours) with rituximab (133 nM), veltuzumab (133 nM), or each of the 3 HexAbs (100 nM). Samples also included rituximab (133 nM) or veltuzumab (133 nM) in the presence of a crosslinking antibody (10 μg/mL). Cells were stained for 30 minutes in the dark at 37° C. with 50 nM of the fluorescent probe tetramethylrhodamine ethyl ester in a medium containing antibiotics and serum, washed 3× with PBS, and analyzed.

Immunoblot Analysis

In general, Daudi or Raji cells (1×10⁶ cells/mL) were treated for a predetermined time with rituximab, veltuzumab, or epratuzumab at 133 or 10 nM, or with 20-20, 20-22, or 22-20 at 10 nM, then washed in PBS, centrifuged, and lysed in ice cold 1× RIPA buffer comprising 2 mM sodium orthovanadate, 5 mM sodium fluoride, 2.5 mM sodium pyrophosphate, 1 mM β-glycerophosphate, and 0.25% sodium deoxycholate. The lysates were centrifuged at 13,000×g, and the supernatants were collected. Protein content was determined using the protein assay kit from Bio-Rad, with bovine serum albumin as the standard. Protein samples (25 μg) were mixed with the lysis buffer and heated at 95° C. for 5 minutes, followed by separation on 4%-20% gradient Tris-glycine gels. Separated proteins were transferred electrophoretically onto nitrocellulose membranes. Nonspecific binding sites were blocked in 10 mM Tris-buffered saline containing 0.05% Tween-20 (TBS-T) and 10% nonfat milk. Membranes were incubated with a primary antibody (1:1000 dilution in TBS-T containing 5% bovine serum albumin) overnight at 4° C. The next day, membranes were washed 3× with TBS-T at room temperature. Horseradish peroxidase-conjugated secondary antibody (1:5000 dilution) was used to probe the primary antibody. Blots were visualized with enhanced chemiluminescence (Thermo Scientific).

RNA Interference of PTEN

Daudi cells were transfected with PTEN small interfering RNA (siRNA; Cell Signaling Technologies) or control siRNA (Santa Cruz Biotechnology) in E-well plates using DMRIE-C, per manufacturer's instructions, then treated with each HexAb at 10 nM for 16 hours. Cells were washed with PBS, stained with annexin V conjugate for 20 minutes, and analyzed by flow cytometry. Controls also included cells incubated with only DMRIE-C. Immunoblot analysis was performed as described above with 5 μg protein samples and anti-PTEN antibody.

Results

Growth Inhibition and Apoptosis

The dose-response curves (FIG. 5A) obtained with the MTS assay from a 3-day treatment of Daudi cells indicated comparable values of EC₅₀ for 20-20, 22-20, and 20-22 (2.3-5.8 nM), which were 100-fold more potent than veltuzumab or rituximab (>500 nM). Under these conditions, crosslinking veltuzumab or rituximab with GAH antibody potently inhibited the proliferation of Daudi cells, with an EC₅₀ of approximately 0.6 nM. Previous results (Rossi et al., Blood 2009, 113:6161-6171) obtained from a cell counting assay at day 5 in Daudi demonstrated lower EC₅₀ values for 22-20 (0.32 nM) and 20-22 (0.5 nM), which may have been due to a longer incubation time (5 vs 3 days), as well as using a different assay (cell counting vs MTS). The 3 HexAbs also inhibited the proliferation of Raji (FIG. 5B), with EC₅₀ values of 6-8 nM, and when tested at 10 nM, were effective in suppressing the growth of RL and DoHH2 (FIG. 5C), as well as CLL specimens (Table 7) from 3 of the 8 patients (CLL078, CLL113, and CLL145) showing higher levels of CD20 expression (Stein et al., Blood 2010, 115:5180-5190). It is noted that under the same conditions and even in the presence of GAH, neither rituximab nor veltuzumab showed significant inhibition (10% or less) of CLL samples from all 8 patients.

TABLE 7 Cytotoxicity of HexAbs on CLL patient specimens as determined by the MTS assay^(#) Patient CD20 Rituximab + Veltuzumab + ID expression Rituximab GAH Veltuzumab GAH 20-20 22-20 20-22 CLL021 Low 114 ± 6 120 ± 6   113 ± 12 103 ± 11 117 ± 2 118 ± 6 114 ± 4  CLL022 Low 102 ± 5 107 ± 5  106 ± 1 102 ± 3  114 ± 1 113 ± 1 99 ± 2 CLL030 Low 107 ± 2 105 ± 2  105 ± 3 105 ± 16 108 ± 3 115 ± 2 104 ± 3  CLL037 Low 107 ± 5 102 ± 18 102 ± 8 90 ± 4 109 ± 4  99 ± 3 96 ± 6 CLL078 Moderate 104 ± 1 98 ± 2 101 ± 3 93 ± 4  74 ± 5  76 ± 1 72 ± 2 CLL113 High 101 ± 1 97 ± 4  92 ± 1 96 ± 3  45 ± 2  43 ± 3 39 ± 5 CLL117 Low 107 ± 9 98 ± 7  98 ± 8 97 ± 1 101 ± 7 102 ± 5 84 ± 2 CLL145 Moderate 100 ± 4 107 ± 3  106 ± 6 101 ± 9   84 ± 1  79 ± 1 73 ± 2 ^(#)Values shown are percentage of untreated controls. Cells were treated with each antibody at 10 nM and, where indicated, GAH at 10 μg/mL. MTS indicates the viability assay using One Solution assay reagent; and GAH, goat anti-human secondary antibody used for cross linking.

We next determined whether the observed growth inhibition would involve apoptosis. As shown in FIG. 5D, treating Daudi cells for 24 hours with the 3 HexAbs resulted in approximately 20%-30% apoptosis at 10 nM, and approximately 25%-35% at 100 nM. In contrast, the parental antibodies (veltuzumab and epratuzumab) and also rituximab, at 10 nM, and epratuzumab at 100 nM, did not induce apoptosis beyond the background levels observed with the untreated control. However, a slight increase was observed for the 2 anti-CD20 antibodies, veltuzumab and rituximab, at 100 nM. These results confirm the findings above that 20-20, 22-20, and 20-22 are effective in inducing apoptosis without the requirement of a crosslinking antibody, and suggest that apoptosis of Daudi cells may be provoked with higher concentrations of a Type I anti-CD20 antibody (Cragg & Glennie, Blood 2004, 103:2738-2743), as represented by veltuzumab or rituximab. Similar results were obtained with Raji cells, in which the 3 HexAbs induced approximately 20%-30% apoptosis when tested at 10 or 100 nM (data not shown).

Differentiation from Anti-IgM and Cross-Linked Anti-CD20

Ligation of the B-cell antigen receptor (BCR) with anti-IgM antibody, or CD20 with veltuzumab or rituximab in the presence of a crosslinking antibody, results in a rapid rise of intracellular calcium (Walshe et al., J Biol Chem 2008, 283:16971-1698). Thus, the inability of the 3 anti-CD20/CD22 HexAbs to induce a significant increase in calcium flux (Rossi et al., Blood 2009, 113:6161-6171; Rossi et al., Cancer Res 2008, 68:8384-8392) suggests the involvement of different signals. Noting that activation of BCR in B cells induces the phosphorylation of Lyn, Syk, and PLCγ2 (Niiro & Clark, Nat Rev Immunol 2002, 2:945-956), we first compared the phosphorylation profiles of these key signaling molecules in Daudi cells treated for 24 hours with the following: 133 nM of epratuzumab, veltuzumab, or rituximab; 10 nM of 20-20, 22-20, or 20-22; or 10 μg/mL of anti-IgM. As shown in FIG. 6A, anti-IgM induced the phosphorylation of Lyn, Syk, and PLCγ2 significantly above the basal levels observed for the untreated cells. In contrast, the 3 HexAbs at 10 nM neither induced the phosphorylation of Syk nor increased the constitutive level of phosphorylated PLCγ2. However, they effectively reduced the constitutive level of phosphorylated Lyn, which was notable within 2 hours, became more prominent with time, and persisted for at least 24 hours (FIG. 6B). Additional studies revealed that the HexAbs diminished the level of phosphorylated Akt (FIG. 6C) and stimulated the expression of Raf-1 kinase inhibition protein (RKIP), which was unchanged with anti-IgM (FIG. 6D). These characteristic changes were also observed for veltuzumab or rituximab at 133 nM (FIG. 6A-C), but not at 10 nM, as shown for phosphorylated Lyn and Akt (FIG. 6E). No appreciable changes were observed with epratuzumab at 10 or 133 nM.

Modulation of the MAPK Pathways

The up-regulation of RKIP prompted us to investigate whether these anti-CD20/CD22 HexAbs modulate mitogen-activated protein kinase (MAPK) pathways. Intracellular signaling by rituximab has been studied intensively and been reported to influence various signaling pathways in B-cell malignancies (Bonavida, Oncogene 2007, 26:3629-3636; Jazirehi et al., Mol Cancer Ther 2003, 2:1183-1193; Jazirehi et al., Cancer Res 2007, 67:1270-1281; Vega et al., Oncogene 2004, 23:3530-40), in particular, the down-regulation of both phosphorylated ERK (extracellular signal regulated kinase) (Jazirehi et al., Cancer Res 2004, 64:7117-7126) and p38 MAPK (Vega et al., Oncogene 2004, 23:3530-40). Daudi cells were treated for 24 hours with 10 nM of 20-20, 20-22, or 22-20, or 133 nM of epratuzumab, veltuzumab, or rituximab, and whole-cell lysates were subjected to immunoblotting using phospho-specific ERK and p38 antibodies, with total ERK, p38, and β-actin serving as controls for comparing the amount of proteins loaded in each sample. As shown in FIG. 7A, both hexavalent monospecific 20-20 and hexavalent bispecific 20-22 and 22-20, when tested at 10 nM, induced more than a 50% decrease in the levels of phosphorylated ERK, which was also observed with veltuzumab or rituximab at 133 nM. In addition, all 3 HexAbs led to a 3-fold increase in the levels of phosphorylated p38, whereas veltuzumab and rituximab appeared to have an opposite or minimal effect on the phosphorylation of p38. Similar results (ie, decrease in phosphorylated ERK and increase in phosphorylated p38) also were observed in Raji cells under the same conditions (data not shown). The time course study in Daudi revealed a continuing decrease of phosphorylated ERK during a 24-hour period, which began to be noticeable at 2 hours after the addition of the HexAbs (FIG. 7B). In contrast, cross-linking veltuzumab or rituximab with GAH resulted in enhanced phosphorylation of both ERK and p38 (FIG. 7C), thus further confirming that the HexAbs act through different mechanisms from hyper cross-linked anti-CD20 antibodies.

NF-κB Pathway, Bcl-2 Family Proteins, and Mitochondrial Membrane Depolarization

Consistent with the observation of increased RKIP and decreased phosphorylation of ERK, which should negatively affect the nuclear factor (NF)-κB pathway, we found a significant reduction in the phosphorylation of IKKα/β and IκBα (FIG. 8A). To account for the enhanced potency of the HexAbs to induce apoptosis, we also probed the expression levels of certain pro- and anti-apoptotic proteins of the Bcl-2 family, and the results (FIG. 8B) convincingly demonstrate the down-regulation of at least 4 anti-apoptotic proteins (Mcl-1, Bcl-xL, Bcl-2, and phospho-BAD), with concurrent up-regulation of one pro-apoptotic protein (Bax) that was evident for 22-20 and 20-22. It is noted that the reduction in the anti-apoptotic phospho-BAD was not due to a parallel decrease in the apoptotic BAD, which remained unchanged. Such alterations in the balance of anti- and pro-apoptotic proteins can change the cell fate from survival to apoptosis. The active modulation of Bcl-2 family proteins further led us to determine whether mitochondrial membrane polarization was involved. Surprisingly, only cross-linked veltuzumab or rituximab, but not the HexAbs, could induce an appreciable loss of mitochondrial membrane potential in Daudi cells over the untreated control (FIG. 8C), although they were all capable of inducing apoptosis under the conditions examined. These results agree with the notion that the HexAbs differ in mechanisms of action from cross-linked veltuzumab or rituximab.

Role of PTEN

The up-regulation of RKIP as well as the down-regulation of the AKT and NF-κB pathways also prompted us to investigate whether the tumor suppressor, PTEN, plays a specific role in the apoptosis induced by the HexAbs. Daudi cells were treated with 10 nM 20-20, 20-22, or 22-20, or with 133 nM of rituximab, and the cellular levels of PTEN were examined at 1, 2, 4, 6, and 24 hours (FIG. 9A). Whereas all 3 HexAbs induced a notable increase in PTEN at 1 hour, which persisted through the next 3-5 hours and returned to the basal level at 24 hours, no appreciable change in PTEN was observed with rituximab during the same period. Because up-regulation of PTEN may result in enhanced apoptosis, down-regulation of PTEN by specific siRNAs (FIG. 9B) should prevent apoptosis, as shown in FIG. 9C. The involvement of PTEN was likewise indicated by the observation that LY294002, the specific inhibitor for PI3K, increased the apoptosis induced by the HexAbs from 20% to 25%-40%, but had no effect on either veltuzumab or rituximab (FIG. 9D).

Deregulation of Cell Cycle

The HexAbs were found to arrest Daudi cells in the G₁ phase at both 100 nM (FIG. 10A) and 10 nM (FIG. 10B). Treating Daudi cells with veltuzumab or rituximab exhibited a similar distribution of various phases as the untreated cells. The deregulation of cell cycle by the HexAbs was associated with the up-regulation of the CDK inhibitors, as shown for p21, p27(Kip1), and Kip2 in FIG. 10C, as well as the down-regulation of cyclin D1 and phosphorylated Rb (FIG. 10D).

Discussion

The HexAbs (20-20, 20-22, and 22-20) share properties of both Type I (rituximab, veltuzumab) and Type II (B1, tositumomab) antibodies (Cragg & Glennie, Blood 2004, 103:2738-2743). Consistent with Type II, the HexAbs are negative for CDC and calcium mobilization, do not require crosslinking for growth inhibition or apoptosis, and induce strong homotypic adhesion; yet, they induce translocation of CD20 to lipid rafts like Type I antibodies (Rossi et al., Blood 2009, 113:6161-6171; Rossi et al., Cancer Res 2008, 68:8384-8392). Unexpectedly, 20-20 inhibited proliferation of Burkitt NHL cell lines, Daudi and Raji, in vitro with considerably greater potency, compared with either Type I or II antibodies (Rossi et al., Cancer Res 2008, 68:8384-8392). Burkitt lymphoma lines, Daudi and Raji, were sensitive to all 3 HexAbs, with similar EC₅₀ values (Rossi et al., Blood 2009, 113:6161-6171; Rossi et al., Cancer Res 2008, 68:8384-8392) to cross-linked veltuzumab or rituximab, whereas non-Burkitt lymphoma lines, RL and DoHH2, depicted approximately 25%-40% inhibition on treatment with 10 nM HexAbs. The decrease in potency could have been due to the formation of visible clumps by RL and DoHH2 cells in suspension.

Direct toxicity of these HexAbs was also evaluated on 8 CLL patient specimens, which varied in their CD20 expression. The 3 specimens expressing moderate to high CD20 showed 30%-60% inhibition by the HexAbs, whereas no significant inhibition was observed in the other 5 specimens with low CD20 expression. Interestingly, neither rituximab nor veltuzumab, with or without crosslinking, produced measurable inhibition. Although these studies suggest a trend in the activity of HexAbs related to CD20 expression, more patient samples are needed to substantiate this. On the other hand, it is intriguing that these multivalent monospecific/bispecific HexAbs depict better anti-lymphoma and anti-leukemia properties than their parental IgGs.

To better elucidate the mechanisms by which direct cell killing is achieved with these hexavalent constructs, we focused here on the investigation of the signaling pathways that are triggered in Daudi cells by the 3 HexAbs, in comparison to those induced by the parental antibodies, with some of the experiments repeated in Raji cells. We also performed selective studies in which human lymphoma cells were treated with anti-IgM antibody to activate the BCR, or with veltuzumab or rituximab in the presence of a cross-linking antibody to enhance the apoptotic potency. Our key findings are summarized as follows: (1) The signaling events triggered by 20-20, 22-20, or 20-22 are quantitatively and qualitatively similar in Daudi cells, but distinct from those induced by anti-IgM. (2) Although veltuzumab and rituximab modify the signaling events in Daudi cells similarly to the hexavalent derivatives, as observed for the ERK and NF-κB pathways, both require a higher concentration to be effective and are less efficient in modulating the cell-cycle regulators that promote growth arrest. In addition, the bivalent veltuzumab and rituximab fail to alter the levels of phosphorylated p38 and PTEN from untreated control, whereas all 3 HexAbs increase phosphorylated p38 and PTEN levels significantly. Similar results were obtained in Raji cells for the decrease in phosphorylated ERKs and the increase in phosphorylated p38. No appreciable change in the basal expression of signaling molecules was observed in Daudi cells upon ligation of CD22 bp epratuzumab. (3) The apoptosis and inhibition of cell proliferation resulting from crosslinking veltuzumab or rituximab with GAH involves signaling events that are distinguishable from those associated with the HexAbs, as manifested in phosphorylated ERK (increase vs decrease), intracellular calcium (increase vs no change), and mitochondrial membrane potential (loss vs no change).

For example, we showed that all 3 HexAbs at 10 nM and the bivalent veltuzumab or rituximab at 133 nM, but not at 10 nM, produced similar results in the observed levels of various phosphorylated proteins, CDK inhibitors, and Bcl-2 family members that are known to mediate proliferation, cell-cycle arrest, and apoptosis. Specifically, we observed a notable decrease in p-Lyn, p-Akt, p-BAD, p-ERK1/2, p-IKKα/β, p-IKBα, Mcl-1, Bcl-2, and Bcl-xl levels in the treated versus untreated cells, indicating that multiple prosurvival pathways were negatively affected, which require a higher threshold for the bivalent antibodies. On the other hand, we also noted that a significant increase in the pro-apoptotic signals (phosphorylated p38 and Bax), the tumor suppressor (PTEN), and the CDK inhibitors (p21 and Kip2) was only observed with the HexAbs. Moreover, only the HexAbs induced G₁ arrest, which apparently augmented their antiproliferative potency. However, clustering of CD20 or both CD20 and CD22 via the HexAbs induced neither a rapid rise in intracellular calcium nor phosphorylation of Lyn, Syk, and PLCγ, which are characteristic of ligating BCR with anti-IgM (Niiro & Clark, Nat Rev Immunol 2002, 2:945-956). The inability of the HexAbs to effect a transient increase in intracellular calcium as well as a notable Δψ_(m), and the down-regulation rather than up-regulation of phosphorylated ERK, also differentiate their action from that induced by crosslinking veltuzumab or rituximab with a secondary antibody.

Additional studies using PTEN siRNA and the PI3K inhibitor, LY294002, suggest that PTEN, which converts PI(3,4,5)P₃ to PI(4,5)P₂, and PI3K, producing PI(3,4,5)P₃ from PI(4,5)P₂, play opposing roles in mediating the direct toxicity induced by the anti-CD20/CD22 HexAbs, for which we show PTEN siRNA mitigates, whereas LY294002 enhances, the apoptotic outcome. Such results suggest that accumulation of PI(4,5)P₂, either via the up-regulation of PTEN or the inhibition of PI3K, may be critical for tipping the balance of survival toward death.

Collectively, our findings are consistent with the view that the potent direct cytotoxicity of 20-20, 22-20, and 20-22 is due to their ability for multivalent binding, which lowers the threshold for modifying multiple signaling pathways, resulting in a new distribution of pro- and anti-apoptotic proteins that promotes growth arrest, apoptosis, and, eventually, cell death. Surprisingly, these effects translated to notable differences with regard to their relative potency for killing normal human B cells versus human Burkitt lymphoma cells ex vivo, where 22-20 and 20-22 showed a higher therapeutic ratio (percentage killing of malignant vs percentage normal B cells), compared with veltuzumab and rituximab (Rossi et al., Blood 2009, 113:6161-6171).

Because neither 22-20 nor 20-22 displayed CDC activity, in contrast to the parental veltuzumab, and although 22-20 was less effective in ADCC than 20-22 or veltuzumab, the presence of 4 Fabs of veltuzumab in 22-20 enhanced the ADCC of epratuzumab, which was found to be moderate but statistically significant (Rossi et al., Blood 2009, 113:6161-6171). Taking into consideration that both 22-20 and 20-22 had a higher therapeutic index ex vivo in terms of relative killing of lymphoma versus normal B cells than their parental antibodies, we speculate that a bispecific anti-CD20/CD22 HexAb may be a more potent class of antilymphoma therapeutic antibodies for clinical use. In terms of treating B-cell lymphomas and leukemias expressing both CD20 and CD22, the results suggest that 22-20, with 4 anti-CD20 Fabs, would be the more effective of the 2 bsAb choices. These experiences stimulate us to study whether bispecific HexAbs against other cancer targets also can acquire different and improved therapeutic properties over their parental bivalent antibody forms.

It will be readily apparent to one skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention. Thus, such additional embodiments are within the scope of the present invention. 

What is claimed is:
 1. A method of treating a B-cell lymphoma or leukemia, comprising administering to a subject with a B-cell lymphoma or leukemia a hexavalent DNL complex comprising: a. a first fusion protein comprising an AD (anchor domain) moiety from the N-terminus of an AKAP protein attached to the C-terminal end of an IgG antibody; and b. four copies of a second fusion protein comprising a DDD (dimerization and docking domain) moiety, wherein the amino acid sequence of the DDD moiety is selected from the group consisting of residues 1-44 of human protein kinase A (PKA) RIIα and residues 1-44 of human PKA RIIβ, attached to the C-terminal end of an antigen-binding antibody fragment; wherein pairs of the DDD sequence form dimers that bind to the AD moiety to form the DNL complex; and wherein the complex binds to human CD20 and human CD22.
 2. The method of claim 1, wherein the IgG antibody binds to human CD20 and the antigen-binding antibody fragment binds to human CD22.
 3. The method of claim 1, wherein the IgG antibody binds to human CD22 and the antigen-binding antibody fragment binds to human CD20.
 4. The method of claim 2, wherein the IgG antibody is hA20.
 5. The method of claim 3, wherein the IgG antibody that binds to human CD22 is epratuzumab.
 6. The method of claim 1, further comprising administering to the subject at least one therapeutic agent selected from the group consisting of a toxin, a chemotherapeutic agent, a drug, a pro-drug, an enzyme, an immunomodulator, an anti-angiogenic agent, a pro-apoptotic agent, a cytokine, and a hormone.
 7. The method of claim 6, wherein the therapeutic agent is selected from the group consisting of aplidin, azaribine, anastrozole, azacytidine, bleomycin, bortezomib, bryostatin-1, busulfan, calicheamycin, camptothecin, 10-hydroxycamptothecin, carmustine, celecoxib, chlorambucil, cisplatinum, irinotecan (CPT-11), SN-38, carboplatin, cladribine, cyclophosphamide, cytarabine, dacarbazine, docetaxel, dactinomycin, daunomycin glucuronide, daunorubicin, dexamethasone, diethylstilbestrol, doxorubicin, doxorubicin glucuronide, epirubicin glucuronide, ethinyl estradiol, estramustine, etoposide, etoposide glucuronide, etoposide phosphate, floxuridine (FUdR), 3′,5′-O-dioleoyl-FudR (FUdR-dO), fludarabine, flutamide, fluorouracil, fluoxymesterone, gemcitabine, hydroxyprogesterone caproate, hydroxyurea, idarubicin, ifosfamide, L-asparaginase, leucovorin, lomustine, mechlorethamine, medroprogesterone acetate, megestrol acetate, melphalan, mercaptopurine, 6-mercaptopurine, methotrexate, mitoxantrone, mithramycin, mitomycin, mitotane, phenyl butyrate, prednisone, procarbazine, paclitaxel, pentostatin, PSI-341, semustine streptozocin, tamoxifen, taxanes, testosterone propionate, thalidomide, thioguanine, thiotepa, teniposide, topotecan, uracil mustard, vinblastine, vinorelbine and vincristine.
 8. The method of claim 6, wherein the therapeutic agent is bortezomib.
 9. The method of claim 6, wherein the therapeutic agent is an enzyme selected from the group consisting of malate dehydrogenase, staphylococcal nuclease, delta-V-steroid isomerase, yeast alcohol dehydrogenase, alpha-glycerophosphate dehydrogenase, triose phosphate isomerase, horseradish peroxidase, alkaline phosphatase, asparaginase, glucose oxidase, beta-galactosidase, ribonuclease, urease, catalase, glucose-6-phosphate dehydrogenase, glucoamylase and acetylcholinesterase.
 10. The method of claim 6, wherein the therapeutic agent is an immunomodulator selected from the group consisting of erythropoietin, thrombopoietin, tumor necrosis factor-α (TNF), granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF), interferon-α, interferon-β, interferon-γ, stem cell growth factor designated “S1 factor”, human growth hormone, N-methionyl human growth hormone, bovine growth hormone, parathyroid hormone, thyroxine, insulin, proinsulin, relaxin, prorelaxin, follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), luteinizing hormone (LH), hepatic growth factor, prostaglandin, fibroblast growth factor, prolactin, placental lactogen, mullerian-inhibiting substance, mouse gonadotropin-associated peptide, inhibin, activin, vascular endothelial growth factor, integrin, NGF-β, platelet-growth factor, TGF-α, TGF-β, insulin-like growth factor-I, insulin-like growth factor-II, macrophage-CSF (M-CSF), IL-1, IL-1α, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-14, IL-15, IL-16, IL-17, IL-18, IL-21, angiostatin, thrombospondin, endostatin and lymphotoxin (LT).
 11. The method of claim 1, wherein the IgG antibody or antigen-binding antibody fragment is conjugated to at least one therapeutic agent selected from the group consisting of a radionuclide, a chemotherapeutic agent, a drug, a pro-drug, a toxin, an enzyme, an immunomodulator, an anti-angiogenic agent, a pro-apoptotic agent, a cytokine and a hormone.
 12. The method of claim 11, wherein the therapeutic agent is selected from the group consisting of aplidin, azaribine, anastrozole, azacytidine, bleomycin, bortezomib, bryostatin-1, busulfan, calicheamycin, camptothecin, 10-hydroxycamptothecin, carmustine, celecoxib, chlorambucil, cisplatinum, irinotecan (CPT-11), SN-38, carboplatin, cladribine, cyclophosphamide, cytarabine, dacarbazine, docetaxel, dactinomycin, daunomycin glucuronide, daunorubicin, dexamethasone, diethylstilbestrol, doxorubicin, doxorubicin glucuronide, epirubicin glucuronide, ethinyl estradiol, estramustine, etoposide, etoposide glucuronide, etoposide phosphate, floxuridine (FUdR), 3′,5′-O-dioleoyl-FudR (FUdR-dO), fludarabine, flutamide, fluorouracil, fluoxymesterone, gemcitabine, hydroxyprogesterone caproate, hydroxyurea, idarubicin, ifosfamide, L-asparaginase, leucovorin, lomustine, mechlorethamine, medroprogesterone acetate, megestrol acetate, melphalan, mercaptopurine, 6-mercaptopurine, methotrexate, mitoxantrone, mithramycin, mitomycin, mitotane, phenyl butyrate, prednisone, procarbazine, paclitaxel, pentostatin, PSI-341, semustine streptozocin, tamoxifen, taxanes, testosterone propionate, thalidomide, thioguanine, thiotepa, teniposide, topotecan, uracil mustard, vinblastine, vinorelbine, vincristine, ricin, abrin, ribonuclease, ranpirnase, rapLR1, DNase I, Staphylococcal enterotoxin-A, pokeweed antiviral protein, gelonin, diphtheria toxin, Pseudomonas exotoxin, and Pseudomonas endotoxin.
 13. The method of claim 11, wherein the therapeutic agent is bortezomib.
 14. The method of claim 11, wherein the therapeutic agent is a radionuclide selected from the group consisting of ^(103m)Rh, ¹⁰³Ru, ¹⁰⁵Rh, ¹⁰⁵Ru, ¹⁰⁷Hg, ¹⁰⁹Pd, ¹¹¹Ag, ¹¹¹In, ^(113m)In, ¹¹C, ^(121m)Te, ^(122m)Te, ¹²⁵I, ^(125m)Te, ¹²⁶I, ¹³¹I, ¹³³I, ¹³N, ¹⁴²Pr, ¹⁴³Pr, ¹⁴⁹Pm, ¹⁵²Dy, ¹⁵³Sm, ¹⁵O, ¹⁶¹Tb, ¹⁶⁵Tm, ¹⁶⁶Dy, ¹⁶⁶Ho, ¹⁶⁷Tm, ¹⁶⁹Er, ¹⁶⁹Yb, ¹⁷⁷Lu, ¹⁸⁶Re, ¹⁸⁸Re, ^(189m)Os, ¹⁸⁹Re, ¹⁹²Ir, ¹⁹⁴Ir, ¹⁹⁷Pt, ¹⁹⁸Au, ¹⁹⁹Au, ²⁰¹Tl, ²⁰³Hg, ²¹¹At, ²¹¹Pb, ²¹²Bi, ²¹²Pb, ²¹³Bi, ²¹⁵Po, ²¹⁷At, ²¹⁹Rn, ²²¹Fr, ²²³Ra, ²²⁴Ac, ²²⁵Ac, ³²P, ³³P, ⁴⁷Sc, ⁵¹Cr, ⁵⁷Co, ⁵⁸Co, ⁵⁹Fe, ⁶²Cu, ⁶⁷Cu, ⁶⁷Ga, ⁷⁵Br, ⁷⁵Se, ⁷⁶Br, ⁷⁷As, ⁷⁷Br, ^(80m)Br, ⁸⁹Sr, ⁹⁰Y, ⁹⁵Ru, ⁹⁷Ru, ⁹⁹Mo and ^(99m)Tc.
 15. The method of claim 11, wherein the therapeutic agent is an enzyme selected from the group consisting of malate dehydrogenase, staphylococcal nuclease, delta-V-steroid isomerase, yeast alcohol dehydrogenase, alpha-glycerophosphate dehydrogenase, triose phosphate isomerase, horseradish peroxidase, alkaline phosphatase, asparaginase, glucose oxidase, beta-galactosidase, ribonuclease, urease, catalase, glucose-6-phosphate dehydrogenase, glucoamylase and acetylcholinesterase.
 16. The method of claim 11, wherein the therapeutic agent is an immunomodulator selected from the group consisting of erythropoietin, thrombopoietin, tumor necrosis factor-α (TNF), granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF), interferon-α, interferon-β, interferon-γ, stem cell growth factor designated “S1 factor”, human growth hormone, N-methionyl human growth hormone, bovine growth hormone, parathyroid hormone, thyroxine, insulin, proinsulin, relaxin, prorelaxin, follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), luteinizing hormone (LH), hepatic growth factor, prostaglandin, fibroblast growth factor, prolactin, placental lactogen, OB protein, mullerian-inhibiting substance, mouse gonadotropin-associated peptide, inhibin, activin, vascular endothelial growth factor, integrin, NGF-β, platelet-growth factor, TGF-α, TGF-β, insulin-like growth factor-I, insulin-like growth factor-II, macrophage-CSF (M-CSF), IL-1, IL-1α, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-14, IL-15, IL-16, IL-17, IL-18, IL-21, IL-25, LIF, FLT-3, angiostatin, thrombospondin, endostatin and lymphotoxin (LT).
 17. The method of claim 1, wherein the B-cell lymphoma or leukemia is selected from the group consisting of acute lymphoblastic leukemia, chronic lymphocytic leukemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma, Burkitt's lymphoma and multiple myeloma. 